Adds true observing -- letting you see what your target sees (#24855)

* bring it back now y'all

* adds a bunch of other changes

* pretty much works at this point

* grep

* Fixes some bugs, still chasing some down

* Add observers to recursive mob check, ensuring they can see messages from their orbitted atom

* tidy some things up

* resolve

* remove unnecessary checks

* Address todos, minor cleanups

* oh dear

* initial testing

* Fix some vulnerabilities (oops)

* Fix some other bugs from testing

* ci fixes

* Add some contingencies against clicking things you shouldn't

* fix some noted bugs

* Add observe to admin jump, improve messaging

* add a few more fixes that should mostly address some runtimes

* oh this wasn't really great

* one last thing

* Fix suit inventory problem

* Remove merge artifact

* Add some missing parens

* Prevents you from observing other ghosts, and should fix the getting stuck outside of your body issue.

* we love testing

* adds to player panel

* Fix more bugs with observers getting stuck outside of their body

* cleans up player panel, verb offerings

* shit

* Update code/_onclick/hud/alert.dm

welp

Co-authored-by: GDN <96800819+GDNgit@users.noreply.github.com>
Signed-off-by: Luc <89928798+lewcc@users.noreply.github.com>

* Fixes some targeting issues

* Fixes targeting on aobserve

* Fix some weird storage bugs

* clean up some doulbed up follow links

* Update code/modules/admin/player_panel.dm

Signed-off-by: Luc <89928798+lewcc@users.noreply.github.com>

* Adds some checks for ghost observe

* Remove mentor debug log

* ahhhhhhhhh that'll do it

* Cleans up some additional checks that were not quite what they should have been

* better logging, too

* mochi review

* one more thing

* Gets robot huds mostly working

* hopefully fix folks not getting observe

* Fix order of operations causing a runtime on qdeleting

* Remove some unnecessary stack traces

* Apply suggestions from code review

Co-authored-by: 1080pCat <96908085+1080pCat@users.noreply.github.com>
Signed-off-by: Luc <89928798+lewcc@users.noreply.github.com>

* Fix bug with items in your inventory disappearing on changing HUD modes

* Fix some bugs with the observe verbs

* possibly fix nullspace issues

* funny review

* missed one

---------

Signed-off-by: Luc <89928798+lewcc@users.noreply.github.com>
Co-authored-by: github-actions <41898282+github-actions[bot]@users.noreply.github.com>
Co-authored-by: GDN <96800819+GDNgit@users.noreply.github.com>
Co-authored-by: S34N <12197162+S34NW@users.noreply.github.com>
Co-authored-by: 1080pCat <96908085+1080pCat@users.noreply.github.com>

code/_onclick/hud/action_button.dm

@@ -16,6 +16,8 @@
 	var/id
 	/// UID of the last thing we hovered over. Used for managing action button dragging.
 	var/last_hovered_ref
+	/// Whether or not this should be shown to observers
+	var/shown_to_observers = FALSE
 	/// Whether or not this button is locked, preventing it from being dragged.
 	var/locked = FALSE
 
@@ -32,8 +34,14 @@
 	return ..()
 
 /atom/movable/screen/movable/action_button/proc/can_use(mob/user)
+	if(isobserver(user))
+		var/mob/dead/observer/dead_mob = user
+		if(dead_mob.mob_observed) // Observers can only click on action buttons if they're not observing something
+			return FALSE
 	if(!linked_action)
 		return TRUE
+	if(linked_action.owner != user)
+		return FALSE
 	return !isnull(linked_action.viewers[user.hud_used])
 
 // Entered and Exited won't fire while you're dragging something, because you're still "holding" it
@@ -60,7 +68,8 @@
 		last_hovered.MouseExited(over_location, over_control, params)
 		closeToolTip(usr)
 	last_hovered_ref = UID(over_object)
-	over_object.MouseEntered(over_location, over_control, params)
+	if(!isnull(over_object))
+		over_object.MouseEntered(over_location, over_control, params)
 
 /atom/movable/screen/movable/action_button/MouseDrop(over_object)
 	last_hovered_ref = null
@@ -113,6 +122,8 @@
 	animate(src, transform = matrix(), time = 0.4 SECONDS, alpha = 255)
 
 /atom/movable/screen/movable/action_button/Click(location, control, params)
+	if(!can_use(usr))
+		return FALSE
 	var/list/modifiers = params2list(params)
 	if(modifiers["ctrl"] && modifiers["shift"])
 		INVOKE_ASYNC(src, PROC_REF(set_to_keybind), usr)
@@ -578,4 +589,47 @@ GLOBAL_LIST_INIT(palette_removed_matrix, list(1.4,0,0,0, 0.7,0.4,0,0, 0.4,0,0.6,
 			button = action.viewers[src]
 		position_action(button, button.location)
 
+
+/**
+ * Show (most) of the another mob's action buttons to this mob
+ *
+ * Used for observers viewing another mob's screen
+ */
+/mob/proc/show_other_mob_action_buttons(mob/take_from)
+	if(!hud_used || !client)
+		return
+
+	for(var/datum/action/action as anything in take_from.actions)
+		if(!action.show_to_observers)
+			continue
+		action.GiveAction(src)
+	RegisterSignal(take_from, COMSIG_MOB_GRANTED_ACTION, PROC_REF(on_observing_action_granted), override = TRUE)
+	RegisterSignal(take_from, COMSIG_MOB_REMOVED_ACTION, PROC_REF(on_observing_action_removed), override = TRUE)
+
+/**
+ * Hide another mob's action buttons from this mob
+ *
+ * Used for observers viewing another mob's screen
+ */
+/mob/proc/hide_other_mob_action_buttons(mob/take_from)
+	for(var/datum/action/action as anything in take_from.actions)
+		action.HideFrom(src)
+	UnregisterSignal(take_from, list(COMSIG_MOB_GRANTED_ACTION, COMSIG_MOB_REMOVED_ACTION))
+
+/// Signal proc for [COMSIG_MOB_GRANTED_ACTION] - If we're viewing another mob's action buttons,
+/// we need to update with any newly added buttons granted to the mob.
+/mob/proc/on_observing_action_granted(mob/living/source, datum/action/action)
+	SIGNAL_HANDLER  // COMSIG_MOB_GRANTED_ACTION
+
+	if(!action.show_to_observers)
+		return
+	action.GiveAction(src)
+
+/// Signal proc for [COMSIG_MOB_REMOVED_ACTION] - If we're viewing another mob's action buttons,
+/// we need to update with any removed buttons from the mob.
+/mob/proc/on_observing_action_removed(mob/living/source, datum/action/action)
+	SIGNAL_HANDLER  // COMSIG_MOB_REMOVED_ACTION
+
+	action.HideFrom(src)
+
 #undef AB_MAX_COLUMNS

code/_onclick/hud/ai_hud.dm

@@ -1,20 +1,27 @@
 /atom/movable/screen/ai
 	icon = 'icons/mob/screen_ai.dmi'
 
+/atom/movable/screen/ai/Click()
+	if(isobserver(usr) || usr.incapacitated())
+		return TRUE
+
 /atom/movable/screen/ai/aicore
 	name = "AI core"
 	icon_state = "ai_core"
 
 /atom/movable/screen/ai/aicore/Click()
-	if(isAI(usr))
-		var/mob/living/silicon/ai/AI = usr
-		AI.view_core()
+	if(..())
+		return
+	var/mob/living/silicon/ai/AI = usr
+	AI.view_core()
 
 /atom/movable/screen/ai/camera_list
 	name = "Show Camera List"
 	icon_state = "camera"
 
 /atom/movable/screen/ai/camera_list/Click()
+	if(..())
+		return
 	var/mob/living/silicon/ai/AI = usr
 	var/camera = tgui_input_list(AI, "Choose which camera you want to view", "Cameras", AI.get_camera_list())
 	AI.ai_camera_list(camera)
@@ -24,53 +31,60 @@
 	icon_state = "track"
 
 /atom/movable/screen/ai/camera_track/Click()
-	if(isAI(usr))
-		var/mob/living/silicon/ai/AI = usr
-		var/target_name = tgui_input_list(AI, "Choose a target you want to track", "Tracking", AI.trackable_mobs())
-		if(target_name)
-			AI.ai_camera_track(target_name)
+	if(..())
+		return
+	var/mob/living/silicon/ai/AI = usr
+	var/target_name = tgui_input_list(AI, "Choose a target you want to track", "Tracking", AI.trackable_mobs())
+	if(target_name)
+		AI.ai_camera_track(target_name)
 
 /atom/movable/screen/ai/camera_light
 	name = "Toggle Camera Light"
 	icon_state = "camera_light"
 
 /atom/movable/screen/ai/camera_light/Click()
-	if(isAI(usr))
-		var/mob/living/silicon/ai/AI = usr
-		AI.toggle_camera_light()
+	if(..())
+		return
+	var/mob/living/silicon/ai/AI = usr
+	AI.toggle_camera_light()
 
 /atom/movable/screen/ai/crew_monitor
 	name = "Crew Monitoring Console"
 	icon_state = "crew_monitor"
 
 /atom/movable/screen/ai/crew_monitor/Click()
-	if(isAI(usr))
-		var/mob/living/silicon/ai/AI = usr
-		AI.subsystem_crew_monitor()
+	if(..())
+		return
+	var/mob/living/silicon/ai/AI = usr
+	AI.subsystem_crew_monitor()
 
 /atom/movable/screen/ai/crew_manifest
 	name = "Crew Manifest"
 	icon_state = "manifest"
 
 /atom/movable/screen/ai/crew_manifest/Click()
-	if(isAI(usr))
-		var/mob/living/silicon/ai/AI = usr
-		AI.ai_roster()
+	if(..())
+		return
+	var/mob/living/silicon/ai/AI = usr
+	AI.ai_roster()
 
 /atom/movable/screen/ai/alerts
 	name = "Show Alerts"
 	icon_state = "alerts"
 
 /atom/movable/screen/ai/alerts/Click()
-	if(isAI(usr))
-		var/mob/living/silicon/ai/AI = usr
-		AI.ai_alerts()
+	if(..())
+		return
+	var/mob/living/silicon/ai/AI = usr
+	AI.ai_alerts()
 
 /atom/movable/screen/ai/announcement
 	name = "Make Announcement"
 	icon_state = "announcement"
 
 /atom/movable/screen/ai/announcement/Click()
+	if(..())
+		return
 	var/mob/living/silicon/ai/AI = usr
 	AI.announcement()
 
@@ -79,15 +93,18 @@
 	icon_state = "call_shuttle"
 
 /atom/movable/screen/ai/call_shuttle/Click()
-	if(isAI(usr))
-		var/mob/living/silicon/ai/AI = usr
-		AI.ai_call_shuttle()
+	if(..())
+		return
+	var/mob/living/silicon/ai/AI = usr
+	AI.ai_call_shuttle()
 
 /atom/movable/screen/ai/state_laws
 	name = "Law Manager"
 	icon_state = "state_laws"
 
 /atom/movable/screen/ai/state_laws/Click()
+	if(..())
+		return
 	if(isAI(usr))
 		var/mob/living/silicon/ai/AI = usr
 		AI.subsystem_law_manager()
@@ -97,42 +114,48 @@
 	icon_state = "pda_send"
 
 /atom/movable/screen/ai/pda_msg_send/Click()
-	if(isAI(usr))
-		var/mob/living/silicon/ai/AI = usr
-		AI.aiPDA.cmd_send_pdamesg()
+	if(..())
+		return
+	var/mob/living/silicon/ai/AI = usr
+	AI.aiPDA.cmd_send_pdamesg()
 
 /atom/movable/screen/ai/pda_msg_show
 	name = "PDA - Show Message Log"
 	icon_state = "pda_receive"
 
 /atom/movable/screen/ai/pda_msg_show/Click()
-	if(isAI(usr))
-		var/mob/living/silicon/ai/AI = usr
-		AI.aiPDA.cmd_show_message_log()
+	if(..())
+		return
+	var/mob/living/silicon/ai/AI = usr
+	AI.aiPDA.cmd_show_message_log()
 
 /atom/movable/screen/ai/image_take
 	name = "Take Image"
 	icon_state = "take_picture"
 
 /atom/movable/screen/ai/image_take/Click()
-	if(isAI(usr))
-		var/mob/living/silicon/ai/AI = usr
-		AI.aiCamera.toggle_camera_mode()
+	if(..())
+		return
+	var/mob/living/silicon/ai/AI = usr
+	AI.aiCamera.toggle_camera_mode()
 
 /atom/movable/screen/ai/image_view
 	name = "View Images"
 	icon_state = "view_images"
 
 /atom/movable/screen/ai/image_view/Click()
-	if(isAI(usr))
-		var/mob/living/silicon/ai/AI = usr
-		AI.aiCamera.viewpictures()
+	if(..())
+		return
+	var/mob/living/silicon/ai/AI = usr
+	AI.aiCamera.viewpictures()
 
 /atom/movable/screen/ai/sensors
 	name = "Toggle Sensor Augmentation"
 	icon_state = "ai_sensor"
 
 /atom/movable/screen/ai/sensors/Click()
+	if(..())
+		return
 	if(isAI(usr))
 		var/mob/living/silicon/ai/AI = usr
 		AI.sensor_mode()

code/_onclick/hud/alert.dm

@@ -48,6 +48,8 @@
 		if(override)
 			alert.timeout = null
 
+		alert.attach_owner(src)
+
 	if(icon_override)
 		alert.icon = icon_override
 
@@ -100,10 +102,50 @@
 	name = "Alert"
 	desc = "Something seems to have gone wrong with this alert, so report this bug please"
 	mouse_opacity = MOUSE_OPACITY_ICON
-	var/timeout = 0 //If set to a number, this alert will clear itself after that many deciseconds
+	/// How long before this alert automatically clears itself (in deciseconds). If zero, remains until cleared.
+	var/timeout = 0
+	/// Some alerts may have different icon states based on severity, this adjusts that.
 	var/severity = 0
+	/// Tool-tip for the alert.
 	var/alerttooltipstyle = ""
-	var/override_alerts = FALSE //If it is overriding other alerts of the same type
+	/// If true, this should override any other alerts of the same type thrown.
+	var/override_alerts = FALSE
+	/// The mob that this alert was originally thrown to.
+	var/mob/owner
+
+/atom/movable/screen/alert/proc/attach_owner(mob/new_owner)
+	owner = new_owner
+	RegisterSignal(owner, COMSIG_PARENT_QDELETING, PROC_REF(remove_owner))
+
+/atom/movable/screen/alert/proc/remove_owner(mob/source, force)
+	SIGNAL_HANDLER  // COMSIG_PARENT_QDELETING
+	if(owner == source && !isnull(owner))
+		UnregisterSignal(owner, COMSIG_PARENT_QDELETING)
+		owner = null
+
+/atom/movable/screen/alert/Destroy()
+	if(owner)
+		UnregisterSignal(owner, COMSIG_PARENT_QDELETING)
+	owner = null
+	severity = 0
+	master = null
+	screen_loc = ""
+	return ..()
+
+/atom/movable/screen/alert/Click(location, control, params)
+	..()
+	if(!usr || !usr.client)
+		return FALSE
+	if(usr != owner)
+		to_chat(usr, "<span class='notice'>Only [owner] can use that!</span>")
+		return FALSE
+	var/paramslist = params2list(params)
+	if(paramslist["shift"]) // screen objects don't do the normal Click() stuff so we'll cheat
+		to_chat(usr, "<span class='boldnotice'>[name]</span> - <span class='info'>[desc]</span>")
+		return FALSE
+	if(master)
+		usr.client.Click(master, location, control, params)
+	return TRUE
 
 /atom/movable/screen/alert/MouseEntered(location, control, params)
 	. = ..()
@@ -310,7 +352,7 @@ or something covering your eyes."
 	icon_state = "embeddedobject"
 
 /atom/movable/screen/alert/embeddedobject/Click()
-	if(isliving(usr))
+	if(isliving(usr) && ..())
 		var/mob/living/carbon/human/M = usr
 		return M.help_shake_act(M)
 
@@ -333,7 +375,7 @@ or shoot a gun to move around via Newton's 3rd Law of Motion."
 	icon_state = "fire"
 
 /atom/movable/screen/alert/fire/Click()
-	if(isliving(usr))
+	if(isliving(usr) && ..())
 		var/mob/living/L = usr
 		return L.resist()
 
@@ -343,7 +385,7 @@ or shoot a gun to move around via Newton's 3rd Law of Motion."
 	icon_state = "direction_lock"
 
 /atom/movable/screen/alert/direction_lock/Click()
-	if(isliving(usr))
+	if(isliving(usr) && ..())
 		var/mob/living/L = usr
 		return L.clear_forced_look()
 
@@ -406,7 +448,7 @@ Recharging stations are available in robotics, the dormitory bathrooms, and the
 	desc = "You have merged with a diona gestalt and are now part of it's biomass. You can still wiggle yourself free though."
 
 /atom/movable/screen/alert/nymph/Click()
-	if(!usr || !usr.client)
+	if(!..())
 		return
 	if(isnymph(usr))
 		var/mob/living/simple_animal/diona/D = usr
@@ -417,7 +459,7 @@ Recharging stations are available in robotics, the dormitory bathrooms, and the
 	desc = "You have merged with one or more diona nymphs. Click here to drop it (or one of them)."
 
 /atom/movable/screen/alert/gestalt/Click()
-	if(!usr || !usr.client)
+	if(!..())
 		return
 
 	var/list/nymphs = list()
@@ -465,7 +507,7 @@ so as to remain in compliance with the most up-to-date laws."
 	return ..()
 
 /atom/movable/screen/alert/hackingapc/Click()
-	if(!usr || !usr.client)
+	if(!..())
 		return
 	if(!target)
 		return
@@ -491,7 +533,7 @@ so as to remain in compliance with the most up-to-date laws."
 	return ..()
 
 /atom/movable/screen/alert/mech_port_available/Click()
-	if(!usr || !usr.client)
+	if(!..())
 		return
 	if(!ismecha(usr.loc) || !target)
 		return
@@ -507,7 +549,7 @@ so as to remain in compliance with the most up-to-date laws."
 	icon_state = "mech_port_x"
 
 /atom/movable/screen/alert/mech_port_disconnect/Click()
-	if(!usr || !usr.client)
+	if(!..())
 		return
 	if(!ismecha(usr.loc))
 		return
@@ -566,7 +608,7 @@ so as to remain in compliance with the most up-to-date laws."
 	timeout = 300
 
 /atom/movable/screen/alert/notify_cloning/Click()
-	if(!usr || !usr.client)
+	if(!..())
 		return
 	var/mob/dead/observer/G = usr
 	G.reenter_corpse()
@@ -585,6 +627,8 @@ so as to remain in compliance with the most up-to-date laws."
 	overlays += I
 
 /atom/movable/screen/alert/ghost/Click()
+	if(!..())
+		return
 	var/mob/living/carbon/human/infected_user = usr
 	if(!istype(infected_user) || infected_user.stat == DEAD)
 		infected_user.clear_alert("ghost_nest")
@@ -640,7 +684,7 @@ so as to remain in compliance with the most up-to-date laws."
 	return ..()
 
 /atom/movable/screen/alert/notify_action/Click()
-	if(!usr || !usr.client)
+	if(!..())
 		return
 	var/mob/dead/observer/G = usr
 
@@ -721,7 +765,7 @@ so as to remain in compliance with the most up-to-date laws."
 	var/stoner = null
 
 /atom/movable/screen/alert/notify_soulstone/Click()
-	if(!usr || !usr.client)
+	if(!..())
 		return
 	if(stone)
 		if(tgui_alert(usr, "Do you want to be captured by [stoner]'s soul stone? This will destroy your corpse and make it \
@@ -738,6 +782,7 @@ so as to remain in compliance with the most up-to-date laws."
 	icon_state = "map_vote"
 
 /atom/movable/screen/alert/notify_mapvote/Click()
+	// ehh sure let observers click on it if they really want, who cares
 	usr.client.vote()
 
 //OBJECT-BASED
@@ -756,11 +801,14 @@ so as to remain in compliance with the most up-to-date laws."
 	desc = "You're legcuffed, which slows you down considerably. Click the alert to free yourself."
 
 /atom/movable/screen/alert/restrained/Click()
-	if(isliving(usr))
-		var/mob/living/L = usr
-		return L.resist()
+	if(!isliving(usr) || !..())
+		return
+	var/mob/living/L = usr
+	return L.resist()
 
 /atom/movable/screen/alert/restrained/buckled/Click()
+	if(!isliving(usr) || !..())
+		return
 	var/mob/living/L = usr
 	if(!istype(L) || !L.can_resist())
 		return
@@ -770,20 +818,23 @@ so as to remain in compliance with the most up-to-date laws."
 // PRIVATE = only edit, use, or override these if you're editing the system as a whole
 
 // Re-render all alerts - also called in /datum/hud/show_hud() because it's needed there
-/datum/hud/proc/reorganize_alerts()
+/datum/hud/proc/reorganize_alerts(mob/viewmob)
+	var/mob/screenmob = viewmob || mymob
+	if(!screenmob.client)
+		return
 	var/list/alerts = mymob.alerts
 	if(!alerts)
 		return FALSE
 	var/icon_pref
 	if(!hud_shown)
 		for(var/i in 1 to length(alerts))
-			mymob.client.screen -= alerts[alerts[i]]
+			screenmob.client.screen -= alerts[alerts[i]]
 		return TRUE
 	for(var/i in 1 to length(alerts))
 		var/atom/movable/screen/alert/alert = alerts[alerts[i]]
 		if(alert.icon_state == "template")
 			if(!icon_pref)
-				icon_pref = ui_style2icon(mymob.client.prefs.UI_style)
+				icon_pref = ui_style2icon(screenmob.client.prefs.UI_style)
 			alert.icon = icon_pref
 		switch(i)
 			if(1)
@@ -799,24 +850,12 @@ so as to remain in compliance with the most up-to-date laws."
 			else
 				. = ""
 		alert.screen_loc = .
-		mymob.client.screen |= alert
+		screenmob.client.screen |= alert
+	if(!viewmob)
+		for(var/viewer in mymob.observers)
+			reorganize_alerts(viewer)
 	return TRUE
 
-/atom/movable/screen/alert/Click(location, control, params)
-	if(!usr || !usr.client)
-		return
-	var/paramslist = params2list(params)
-	if(paramslist["shift"]) // screen objects don't do the normal Click() stuff so we'll cheat
-		to_chat(usr, "<span class='boldnotice'>[name]</span> - <span class='info'>[desc]</span>")
-		return
-	if(master)
-		return usr.client.Click(master, location, control, params)
-
-/atom/movable/screen/alert/Destroy()
-	severity = 0
-	master = null
-	screen_loc = ""
-	return ..()
 
 /// Gives the player the option to succumb while in critical condition
 /atom/movable/screen/alert/succumb
@@ -825,7 +864,7 @@ so as to remain in compliance with the most up-to-date laws."
 	icon_state = "succumb"
 
 /atom/movable/screen/alert/succumb/Click()
-	if(!usr || !usr.client)
+	if(!..())
 		return
 	var/mob/living/living_owner = usr
 	if(!istype(usr))

code/_onclick/hud/alien_hud.dm

@@ -146,19 +146,22 @@
 			inv_slots[inv.slot_id] = inv
 			inv.update_icon()
 
-/datum/hud/alien/persistent_inventory_update()
+/datum/hud/alien/persistent_inventory_update(mob/viewer)
 	if(!mymob)
 		return
 	var/mob/living/carbon/alien/humanoid/H = mymob
+	var/mob/screenmob = viewer || H
 	if(hud_version != HUD_STYLE_NOHUD)
 		if(H.r_hand)
 			H.r_hand.screen_loc = ui_rhand
-			H.client.screen += H.r_hand
+			screenmob.client.screen += H.r_hand
 		if(H.l_hand)
 			H.l_hand.screen_loc = ui_lhand
-			H.client.screen += H.l_hand
+			screenmob.client.screen += H.l_hand
 	else
 		if(H.r_hand)
 			H.r_hand.screen_loc = null
+			screenmob.client.screen -= H.r_hand
 		if(H.l_hand)
 			H.l_hand.screen_loc = null
+			screenmob.client.screen -= H.l_hand

code/_onclick/hud/fullscreen.dm

@@ -49,16 +49,17 @@
 	for(var/category in screens)
 		clear_fullscreen(category)
 
-/datum/hud/proc/reload_fullscreen()
-	if(mymob.client)
-		var/atom/movable/screen/fullscreen/screen
-		var/list/screens = mymob.screens
-		for(var/category in screens)
-			screen = screens[category]
-			if(screen.should_show_to(mymob))
-				mymob.client.screen |= screen
-				continue
-			mymob.client.screen -= screen
+/mob/proc/reload_fullscreen()
+	if(!client)
+		return
+	var/atom/movable/screen/fullscreen/screen
+	for(var/category in screens)
+		screen = screens[category]
+		if(screen.should_show_to(src))
+			screen.update_for_view(client.view)
+			client.screen |= screen
+		else
+			client.screen -= screen
 
 /atom/movable/screen/fullscreen
 	icon = 'icons/mob/screen_full.dmi'

code/_onclick/hud/ghost_hud.dm

@@ -110,7 +110,24 @@
 	for(var/atom/movable/screen/S in (static_inventory + toggleable_inventory))
 		S.hud = src
 
-/datum/hud/ghost/show_hud()
-	mymob.client.screen = list()
-	mymob.client.screen += static_inventory
-	..()
+/datum/hud/ghost/show_hud(version = 0, mob/viewmob)
+	// don't show this HUD if observing; show the HUD of the observee
+	var/mob/dead/observer/O = mymob
+	if(istype(O) && O.mob_observed)
+		plane_masters_update()
+		return FALSE
+
+	. = ..()
+	if(!.)
+		return
+	var/mob/screenmob = viewmob || mymob
+	screenmob.client.screen += static_inventory
+
+
+// We should only see observed mob alerts.
+/datum/hud/ghost/reorganize_alerts(mob/viewmob)
+	var/mob/dead/observer/O = mymob
+	if(istype(O) && O.mob_observed)
+		return
+	return ..()
+

code/_onclick/hud/hud_datum.dm

@@ -11,7 +11,7 @@
 	var/hud_shown = TRUE
 	/// Current displayed version of the HUD
 	var/hud_version = 1
-	/// Whether or not their toggleable inventory
+	/// Whether or not their toggleable inventory (generally their contents on the left) is expanded
 	var/inventory_shown = TRUE
 	/// This is to hide the buttons that can be used via hotkeys. (hotkeybuttons list of buttons)
 	var/hotkey_ui_hidden = FALSE
@@ -147,14 +147,22 @@
 	QDEL_NULL(screentip_text)
 	return ..()
 
-/datum/hud/proc/show_hud(version = 0)
+/**
+ * Shows this hud's hud to some mob
+ *
+ * Arguments
+ * * version - denotes which style should be displayed. blank or 0 means "next version"
+ * * viewmob - what mob to show the hud to. Can be this hud's mob, can be another mob, can be null (will use this hud's mob if so)
+ */
+/datum/hud/proc/show_hud(version = 0, mob/viewmob)
 	if(!ismob(mymob))
 		return FALSE
-
-	if(!mymob.client)
+	var/mob/screenmob = viewmob || mymob
+	if(!screenmob.client)
 		return FALSE
 
-	mymob.client.screen = list()
+	screenmob.client.clear_screen()
+	screenmob.client.apply_clickcatcher()
 
 	var/display_hud_version = version
 	if(!display_hud_version)	//If 0 or blank, display the next hud version
@@ -166,15 +174,15 @@
 		if(HUD_STYLE_STANDARD)	//Default HUD
 			hud_shown = TRUE	//Governs behavior of other procs
 			if(length(static_inventory))
-				mymob.client.screen += static_inventory
-			if(length(toggleable_inventory) && inventory_shown)
-				mymob.client.screen += toggleable_inventory
-			if(length(hotkeybuttons) && !hotkey_ui_hidden)
-				mymob.client.screen += hotkeybuttons
+				screenmob.client.screen += static_inventory
+			if(length(toggleable_inventory) && screenmob.hud_used?.inventory_shown)
+				screenmob.client.screen += toggleable_inventory
+			if(length(hotkeybuttons) && !screenmob.hud_used?.hotkey_ui_hidden)
+				screenmob.client.screen += hotkeybuttons
 			if(length(infodisplay))
-				mymob.client.screen += infodisplay
+				screenmob.client.screen += infodisplay
 
-			mymob.client.screen += toggle_palette
+			screenmob.client.screen += toggle_palette
 
 			if(action_intent)
 				action_intent.screen_loc = initial(action_intent.screen_loc) //Restore intent selection to the original position
@@ -182,33 +190,33 @@
 		if(HUD_STYLE_REDUCED)	//Reduced HUD
 			hud_shown = FALSE	//Governs behavior of other procs
 			if(length(static_inventory))
-				mymob.client.screen -= static_inventory
+				screenmob.client.screen -= static_inventory
 			if(length(toggleable_inventory))
-				mymob.client.screen -= toggleable_inventory
+				screenmob.client.screen -= toggleable_inventory
 			if(length(hotkeybuttons))
-				mymob.client.screen -= hotkeybuttons
+				screenmob.client.screen -= hotkeybuttons
 			if(length(infodisplay))
-				mymob.client.screen += infodisplay
+				screenmob.client.screen += infodisplay
 
 			//These ones are a part of 'static_inventory', 'toggleable_inventory' or 'hotkeybuttons' but we want them to stay
 			if(inv_slots[SLOT_HUD_LEFT_HAND])
-				mymob.client.screen += inv_slots[SLOT_HUD_LEFT_HAND]	//we want the hands to be visible
+				screenmob.client.screen += inv_slots[SLOT_HUD_LEFT_HAND]	//we want the hands to be visible
 			if(inv_slots[SLOT_HUD_RIGHT_HAND])
-				mymob.client.screen += inv_slots[SLOT_HUD_RIGHT_HAND]	//we want the hands to be visible
+				screenmob.client.screen += inv_slots[SLOT_HUD_RIGHT_HAND]	//we want the hands to be visible
 			if(action_intent)
-				mymob.client.screen += action_intent		//we want the intent switcher visible
+				screenmob.client.screen += action_intent		//we want the intent switcher visible
 				action_intent.screen_loc = ui_acti_alt	//move this to the alternative position, where zone_select usually is.
 
 		if(HUD_STYLE_NOHUD)	//No HUD
 			hud_shown = FALSE	//Governs behavior of other procs
 			if(length(static_inventory))
-				mymob.client.screen -= static_inventory
+				screenmob.client.screen -= static_inventory
 			if(length(toggleable_inventory))
-				mymob.client.screen -= toggleable_inventory
+				screenmob.client.screen -= toggleable_inventory
 			if(length(hotkeybuttons))
-				mymob.client.screen -= hotkeybuttons
+				screenmob.client.screen -= hotkeybuttons
 			if(length(infodisplay))
-				mymob.client.screen -= infodisplay
+				screenmob.client.screen -= infodisplay
 
 		if(HUD_STYLE_ACTIONHUD)	//No HUD
 			hud_shown = TRUE	//Governs behavior of other procs
@@ -220,36 +228,46 @@
 				mymob.client.screen -= infodisplay
 
 	hud_version = display_hud_version
-	persistent_inventory_update()
-	mymob.update_action_buttons(1)
-	reorganize_alerts()
-	reload_fullscreen()
-	update_parallax_pref(mymob)
+	persistent_inventory_update(screenmob)
+	screenmob.update_action_buttons(TRUE)
+	reorganize_alerts(screenmob)
+	screenmob.reload_fullscreen()
+	update_parallax_pref(screenmob)
+	if(!viewmob)
+		// working off of mymob
+		plane_masters_update()
+		for(var/M in mymob.observers)
+			show_hud(hud_version, M)
+	else if(viewmob.hud_used)
+		viewmob.hud_used.plane_masters_update()
+		viewmob.show_other_mob_action_buttons(mymob)
 	plane_masters_update()
+	return TRUE
 
 /datum/hud/proc/plane_masters_update()
 	// Plane masters are always shown to OUR mob, never to observers
 	for(var/thing in plane_masters)
 		var/atom/movable/screen/plane_master/PM = plane_masters[thing]
 		PM.backdrop(mymob)
-		mymob.client.screen += PM
+		mymob.client?.screen += PM
 
-/datum/hud/human/show_hud(version = 0)
+/datum/hud/human/show_hud(version = 0, mob/viewmob)
 	. = ..()
 	if(!.)
 		return
-	hidden_inventory_update()
+	var/mob/screenmob = viewmob || mymob
+	hidden_inventory_update(screenmob)
 
-/datum/hud/robot/show_hud(version = 0)
+/datum/hud/robot/show_hud(version = 0, mob/viewmob)
 	. = ..()
 	if(!.)
 		return
-	update_robot_modules_display()
+	update_robot_modules_display(viewmob)
 
-/datum/hud/proc/hidden_inventory_update()
+/datum/hud/proc/hidden_inventory_update(mob/viewer)
 	return
 
-/datum/hud/proc/persistent_inventory_update()
+/datum/hud/proc/persistent_inventory_update(mob/viewer)
 	return
 
 /mob/proc/hide_hud()

code/_onclick/hud/human_hud.dm

@@ -6,14 +6,22 @@
 	icon_state = "toggle"
 
 /atom/movable/screen/human/toggle/Click()
-	if(usr.hud_used.inventory_shown)
+
+	var/mob/targetmob = usr
+
+	if(isobserver(usr))
+		if(ishuman(usr.client.eye) && (usr.client.eye != usr))
+			var/mob/M = usr.client.eye
+			targetmob = M
+
+	if(usr.hud_used.inventory_shown && targetmob.hud_used)
 		usr.hud_used.inventory_shown = FALSE
-		usr.client.screen -= usr.hud_used.toggleable_inventory
+		usr.client.screen -= targetmob.hud_used.toggleable_inventory
 	else
 		usr.hud_used.inventory_shown = TRUE
-		usr.client.screen += usr.hud_used.toggleable_inventory
+		usr.client.screen += targetmob.hud_used.toggleable_inventory
 
-	usr.hud_used.hidden_inventory_update()
+	targetmob.hud_used.hidden_inventory_update(usr)
 
 /atom/movable/screen/human/equip
 	name = "equip"
@@ -21,7 +29,7 @@
 
 /atom/movable/screen/human/equip/Click()
 	if(ismecha(usr.loc)) // stops inventory actions in a mech
-		return 1
+		return TRUE
 	var/mob/living/carbon/human/H = usr
 	H.quick_equip()
 
@@ -33,6 +41,8 @@
 	screen_loc = ui_lingstingdisplay
 
 /atom/movable/screen/ling/sting/Click()
+	if(isobserver(usr))
+		return
 	var/datum/antagonist/changeling/cling = usr.mind.has_antag_datum(/datum/antagonist/changeling)
 	cling?.chosen_sting?.unset_sting()
 
@@ -389,100 +399,118 @@
 		else
 			crafting.invisibility = initial(crafting.invisibility)
 
-/datum/hud/human/hidden_inventory_update()
+/datum/hud/human/hidden_inventory_update(mob/viewer)
 	if(!mymob)
 		return
 	var/mob/living/carbon/human/H = mymob
-	if(inventory_shown && hud_version == HUD_STYLE_STANDARD)
+
+	var/mob/screenmob = viewer || H
+	if(screenmob.hud_used.inventory_shown && screenmob.hud_used.hud_shown && screenmob.hud_used.hud_version == HUD_STYLE_STANDARD)
+
 		if(H.shoes)
 			H.shoes.screen_loc = ui_shoes
-			H.client.screen += H.shoes
+			screenmob.client.screen += H.shoes
 		if(H.gloves)
 			H.gloves.screen_loc = ui_gloves
-			H.client.screen += H.gloves
+			screenmob.client.screen += H.gloves
 		if(H.l_ear)
 			H.l_ear.screen_loc = ui_l_ear
-			H.client.screen += H.l_ear
+			screenmob.client.screen += H.l_ear
 		if(H.r_ear)
 			H.r_ear.screen_loc = ui_r_ear
-			H.client.screen += H.r_ear
+			screenmob.client.screen += H.r_ear
 		if(H.glasses)
 			H.glasses.screen_loc = ui_glasses
-			H.client.screen += H.glasses
+			screenmob.client.screen += H.glasses
 		if(H.w_uniform)
 			H.w_uniform.screen_loc = ui_iclothing
-			H.client.screen += H.w_uniform
+			screenmob.client.screen += H.w_uniform
 		if(H.wear_suit)
 			H.wear_suit.screen_loc = ui_oclothing
-			H.client.screen += H.wear_suit
+			screenmob.client.screen += H.wear_suit
 		if(H.wear_mask)
 			H.wear_mask.screen_loc = ui_mask
-			H.client.screen += H.wear_mask
+			screenmob.client.screen += H.wear_mask
 		if(H.head)
 			H.head.screen_loc = ui_head
-			H.client.screen += H.head
+			screenmob.client.screen += H.head
 	else
-		if(H.shoes)		H.shoes.screen_loc = null
-		if(H.gloves)	H.gloves.screen_loc = null
-		if(H.l_ear)		H.l_ear.screen_loc = null
-		if(H.r_ear)		H.r_ear.screen_loc = null
-		if(H.glasses)	H.glasses.screen_loc = null
-		if(H.w_uniform)	H.w_uniform.screen_loc = null
-		if(H.wear_suit)	H.wear_suit.screen_loc = null
-		if(H.wear_mask)	H.wear_mask.screen_loc = null
-		if(H.head)		H.head.screen_loc = null
+		if(H.shoes)
+			screenmob.client.screen -= H.shoes
+		if(H.gloves)
+			screenmob.client.screen -= H.gloves
+		if(H.l_ear)
+			screenmob.client.screen -= H.l_ear
+		if(H.r_ear)
+			screenmob.client.screen -= H.r_ear
+		if(H.glasses)
+			screenmob.client.screen -= H.glasses
+		if(H.w_uniform)
+			screenmob.client.screen -= H.w_uniform
+		if(H.wear_suit)
+			screenmob.client.screen -= H.wear_suit
+		if(H.wear_mask)
+			screenmob.client.screen -= H.wear_mask
+		if(H.head)
+			screenmob.client.screen -= H.head
 
-/datum/hud/human/persistent_inventory_update()
+/datum/hud/human/persistent_inventory_update(mob/viewer)
 	if(!mymob)
 		return
+	..()
 	var/mob/living/carbon/human/H = mymob
-	if(hud_version == HUD_STYLE_STANDARD)
-		if(H.s_store)
-			H.s_store.screen_loc = ui_sstore1
-			H.client.screen += H.s_store
-		if(H.wear_id)
-			H.wear_id.screen_loc = ui_id
-			H.client.screen += H.wear_id
-		if(H.wear_pda)
-			H.wear_pda.screen_loc = ui_pda
-			H.client.screen += H.wear_pda
-		if(H.belt)
-			H.belt.screen_loc = ui_belt
-			H.client.screen += H.belt
-		if(H.back)
-			H.back.screen_loc = ui_back
-			H.client.screen += H.back
-		if(H.l_store)
-			H.l_store.screen_loc = ui_storage1
-			H.client.screen += H.l_store
-		if(H.r_store)
-			H.r_store.screen_loc = ui_storage2
-			H.client.screen += H.r_store
-	else
-		if(H.s_store)
-			H.s_store.screen_loc = null
-		if(H.wear_id)
-			H.wear_id.screen_loc = null
-		if(H.wear_pda)
-			H.wear_pda.screen_loc = null
-		if(H.belt)
-			H.belt.screen_loc = null
-		if(H.back)
-			H.back.screen_loc = null
-		if(H.l_store)
-			H.l_store.screen_loc = null
-		if(H.r_store)
-			H.r_store.screen_loc = null
+	var/mob/screenmob = viewer || H
+
+	if(screenmob.hud_used)
+		if(screenmob.hud_used.hud_shown && screenmob.hud_used.hud_version == HUD_STYLE_STANDARD)
+			if(H.s_store)
+				H.s_store.screen_loc = ui_sstore1
+				screenmob.client.screen += H.s_store
+			if(H.wear_id)
+				H.wear_id.screen_loc = ui_id
+				screenmob.client.screen += H.wear_id
+			if(H.wear_pda)
+				H.wear_pda.screen_loc = ui_pda
+				screenmob.client.screen += H.wear_pda
+			if(H.belt)
+				H.belt.screen_loc = ui_belt
+				screenmob.client.screen += H.belt
+			if(H.back)
+				H.back.screen_loc = ui_back
+				screenmob.client.screen += H.back
+			if(H.l_store)
+				H.l_store.screen_loc = ui_storage1
+				screenmob.client.screen += H.l_store
+			if(H.r_store)
+				H.r_store.screen_loc = ui_storage2
+				screenmob.client.screen += H.r_store
+		else
+			if(H.s_store)
+				screenmob.client.screen -= H.s_store
+			if(H.wear_id)
+				screenmob.client.screen -= H.wear_id
+			if(H.wear_pda)
+				screenmob.client.screen -= H.wear_pda
+			if(H.belt)
+				screenmob.client.screen -= H.belt
+			if(H.back)
+				screenmob.client.screen -= H.back
+			if(H.l_store)
+				screenmob.client.screen -= H.l_store
+			if(H.r_store)
+				screenmob.client.screen -= H.r_store
 
 	if(hud_version != HUD_STYLE_NOHUD)
 		if(H.r_hand)
 			H.r_hand.screen_loc = ui_rhand
-			H.client.screen += H.r_hand
+			screenmob.client.screen += H.r_hand
 		if(H.l_hand)
 			H.l_hand.screen_loc = ui_lhand
-			H.client.screen += H.l_hand
+			screenmob.client.screen += H.l_hand
 	else
 		if(H.r_hand)
-			H.r_hand.screen_loc = null
+			screenmob.r_hand.screen_loc = null
+			screenmob.client.screen -= H.r_hand
 		if(H.l_hand)
-			H.l_hand.screen_loc = null
+			screenmob.l_hand.screen_loc = null
+			screenmob.client.screen -= H.l_hand

code/_onclick/hud/parallax.dm

@@ -1,6 +1,9 @@
-/datum/hud/proc/create_parallax()
-	var/client/C = mymob.client
-	if(!apply_parallax_pref())
+/datum/hud/proc/create_parallax(mob/viewmob)
+	var/mob/screenmob = viewmob || mymob
+	if(!screenmob.client)
+		return
+	var/client/C = screenmob.client
+	if(!apply_parallax_pref(screenmob))
 		return
 	// this is needed so it blends properly with the space plane and blackness plane.
 	var/atom/movable/screen/plane_master/space/S = plane_masters["[PLANE_SPACE]"]
@@ -34,16 +37,20 @@
 
 	C.screen |= (C.parallax_layers + C.parallax_static_layers_tail)
 
-/datum/hud/proc/remove_parallax()
-	var/client/C = mymob.client
+/datum/hud/proc/remove_parallax(mob/viewmob)
+	var/mob/screenmob = viewmob || mymob
+	var/client/C = screenmob.client
 	C.screen -= (C.parallax_layers_cached + C.parallax_static_layers_tail)
 	C.parallax_layers = null
 	var/atom/movable/screen/plane_master/space/S = plane_masters["[PLANE_SPACE]"]
 	S.color = null
 	S.appearance_flags &= ~NO_CLIENT_COLOR
 
-/datum/hud/proc/apply_parallax_pref()
-	var/client/C = mymob.client
+/datum/hud/proc/apply_parallax_pref(mob/viewmob)
+	var/mob/screen_mob = viewmob || mymob
+	var/client/C = screen_mob.client
+	if(!istype(C))
+		return FALSE
 	if(C.prefs)
 		var/pref = C.prefs.parallax
 		if(isnull(pref))
@@ -72,16 +79,22 @@
 	C.parallax_layers_max = 4
 	return TRUE
 
-/datum/hud/proc/update_parallax_pref()
-	remove_parallax()
-	create_parallax()
-	update_parallax()
+/datum/hud/proc/update_parallax_pref(mob/viewmob)
+	var/mob/screen_mob = viewmob || mymob
+	if(!screen_mob.client)
+		return
+	remove_parallax(screen_mob)
+	create_parallax(screen_mob)
+	update_parallax(screen_mob)
 
 // This sets which way the current shuttle is moving (returns true if the shuttle has stopped moving so the caller can append their animation)
 // Well, it would if our shuttle code had dynamic areas
-/datum/hud/proc/set_parallax_movedir(new_parallax_movedir, skip_windups)
+/datum/hud/proc/set_parallax_movedir(mob/viewmob, new_parallax_movedir, skip_windups)
 	. = FALSE
-	var/client/C = mymob.client
+	var/mob/screen_mob = viewmob || mymob
+	var/client/C = screen_mob.client
+	if(!istype(C))
+		return
 	if(new_parallax_movedir == C.parallax_movedir)
 		return
 	var/animatedir = new_parallax_movedir
@@ -157,8 +170,9 @@
 		animate(L, transform = L.transform, time = 0, loop = -1, flags = ANIMATION_END_NOW)
 		animate(transform = matrix(), time = T)
 
-/datum/hud/proc/update_parallax()
-	var/client/C = mymob.client
+/datum/hud/proc/update_parallax(mob/viewmob)
+	var/mob/screenmob = viewmob || mymob
+	var/client/C = screenmob.client
 	var/turf/posobj = get_turf(C.eye)
 	if(!posobj)
 		return
@@ -167,9 +181,9 @@
 	// Update the movement direction of the parallax if necessary (for shuttles)
 	var/area/shuttle/SA = areaobj
 	if(!SA || !SA.moving)
-		set_parallax_movedir(0)
+		set_parallax_movedir(screenmob, 0)
 	else
-		set_parallax_movedir(SA.parallax_move_direction)
+		set_parallax_movedir(screenmob, SA.parallax_move_direction)
 
 	var/force
 	if(!C.previous_turf || (C.previous_turf.z != posobj.z))
@@ -193,7 +207,7 @@
 
 	for(var/thing in C.parallax_layers)
 		var/atom/movable/screen/parallax_layer/L = thing
-		L.update_status(mymob)
+		L.update_status(screenmob)
 		if(L.view_sized != C.view)
 			L.update_o(C.view)
 

code/_onclick/hud/robot_hud.dm

@@ -1,23 +1,34 @@
 /atom/movable/screen/robot
 	icon = 'icons/mob/screen_robot.dmi'
 
+/atom/movable/screen/robot/Click()
+	. = ..()
+	if(isobserver(usr))
+		return TRUE
+
 /atom/movable/screen/robot/module
 	name = "cyborg module"
 	icon_state = "nomod"
 
 /atom/movable/screen/robot/module/Click()
-	if(isrobot(usr))
+	if(isrobot(usr) && !..())
 		var/mob/living/silicon/robot/R = usr
-		if(R.module)
-			R.hud_used.toggle_show_robot_modules()
-			return 1
-		R.pick_module()
+		if(!R.module)
+			R.pick_module()
+			return
+
+	// we can let ghosts mess with this one
+	usr.hud_used.toggle_show_robot_modules(usr)
+	return TRUE
+
 
 /atom/movable/screen/robot/module1
 	name = "module1"
 	icon_state = "inv1"
 
 /atom/movable/screen/robot/module1/Click()
+	if(..())
+		return
 	if(isrobot(usr))
 		var/mob/living/silicon/robot/R = usr
 		R.toggle_module(1)
@@ -27,6 +38,8 @@
 	icon_state = "inv2"
 
 /atom/movable/screen/robot/module2/Click()
+	if(..())
+		return
 	if(isrobot(usr))
 		var/mob/living/silicon/robot/R = usr
 		R.toggle_module(2)
@@ -36,6 +49,8 @@
 	icon_state = "inv3"
 
 /atom/movable/screen/robot/module3/Click()
+	if(..())
+		return
 	if(isrobot(usr))
 		var/mob/living/silicon/robot/R = usr
 		R.toggle_module(3)
@@ -46,6 +61,8 @@
 	icon_state = "radio"
 
 /atom/movable/screen/robot/radio/Click()
+	if(..())
+		return
 	if(issilicon(usr))
 		var/mob/living/silicon/robot/R = usr
 		R.radio_menu()
@@ -55,6 +72,8 @@
 	icon_state = "store"
 
 /atom/movable/screen/robot/store/Click()
+	if(..())
+		return
 	if(isrobot(usr))
 		var/mob/living/silicon/robot/R = usr
 		R.uneq_active()
@@ -66,6 +85,8 @@
 	screen_loc = ui_borg_lamp
 
 /atom/movable/screen/robot/lamp/Click()
+	if(..())
+		return
 	if(isrobot(usr))
 		var/mob/living/silicon/robot/R = usr
 		R.control_headlamp()
@@ -75,6 +96,8 @@
 	icon_state = "ionpulse0"
 
 /atom/movable/screen/robot/thrusters/Click()
+	if(..())
+		return
 	var/mob/living/silicon/robot/R = usr
 	R.toggle_ionpulse()
 
@@ -83,11 +106,23 @@
 	icon_state = "running"
 
 /atom/movable/screen/robot/mov_intent/Click()
+	if(..())
+		return
 	usr.toggle_move_intent()
 
+/datum/hud/robot
+	var/shown_robot_modules = FALSE	// Used to determine whether they have the module menu shown or not
+	var/atom/movable/screen/robot_modules_background
+
 /datum/hud/robot/New(mob/user)
 	..()
 
+
+	robot_modules_background = new()
+	robot_modules_background.icon_state = "block"
+	robot_modules_background.layer = HUD_LAYER // Objects that appear on screen are on layer 20, UI should be just below it.
+	robot_modules_background.plane = HUD_PLANE
+
 	var/atom/movable/screen/using
 	var/mob/living/silicon/robot/mymobR = mymob
 
@@ -184,41 +219,51 @@
 
 	return ..()
 
-/datum/hud/proc/toggle_show_robot_modules()
+/datum/hud/proc/toggle_show_robot_modules(mob/viewmob)
+	return
+
+/datum/hud/robot/toggle_show_robot_modules(mob/viewmob)
+	var/mob/screenmob = viewmob || mymob
+	if(istype(viewmob.hud_used, /datum/hud/robot))
+		var/datum/hud/robot/robohud = screenmob.hud_used
+		robohud.shown_robot_modules = !robohud.shown_robot_modules
+
+	update_robot_modules_display(viewmob)
+
+/datum/hud/proc/update_robot_modules_display(mob/viewer)
+	return
+
+/datum/hud/robot/update_robot_modules_display(mob/viewer)
 	if(!isrobot(mymob))
 		return
 
 	var/mob/living/silicon/robot/R = mymob
 
-	R.shown_robot_modules = !R.shown_robot_modules
-	update_robot_modules_display()
-
-/datum/hud/proc/update_robot_modules_display()
-	if(!isrobot(mymob))
-		return
-
-	var/mob/living/silicon/robot/R = mymob
+	var/mob/screenmob = viewer || R
 
 	if(!R.client)
 		return
 
 	if(!R.module)
+		shown_robot_modules = FALSE
+		screenmob.client.screen -= robot_modules_background
+		screenmob.client?.screen -= screenmob.hud_used.module_store_icon
 		return
 
-	if(R.shown_robot_modules && hud_version == HUD_STYLE_STANDARD)
+	if(shown_robot_modules && hud_shown && hud_version == HUD_STYLE_STANDARD)
 		//Modules display is shown
-		R.client.screen += module_store_icon	//"store" icon
+		screenmob.client.screen += module_store_icon	//"store" icon
 
 		if(!R.module.modules)
 			to_chat(usr, "<span class='danger'>Selected module has no modules to select.</span>")
 			return
 
-		if(!R.robot_modules_background)
+		if(!robot_modules_background)
 			return
 
 		var/display_rows = CEILING(length(R.module.modules) / 8, 1)
-		R.robot_modules_background.screen_loc = "CENTER-4:16,SOUTH+1:7 to CENTER+3:16,SOUTH+[display_rows]:7"
-		R.client.screen += R.robot_modules_background
+		robot_modules_background.screen_loc = "CENTER-4:16,SOUTH+1:7 to CENTER+3:16,SOUTH+[display_rows]:7"
+		screenmob.client.screen += robot_modules_background
 
 		var/x = -4	//Start at CENTER-4,SOUTH+1
 		var/y = 1
@@ -226,7 +271,7 @@
 		for(var/atom/movable/A in R.module.modules)
 			if((A != R.module_state_1) && (A != R.module_state_2) && (A != R.module_state_3))
 				//Module is not currently active
-				R.client.screen += A
+				screenmob.client.screen += A
 				if(x < 0)
 					A.screen_loc = "CENTER[x]:16,SOUTH+[y]:7"
 				else
@@ -241,11 +286,39 @@
 
 	else
 		//Modules display is hidden
-		R.client.screen -= module_store_icon
+		screenmob.client.screen -= module_store_icon
 
 		for(var/atom/A in R.module.modules)
 			if((A != R.module_state_1) && (A != R.module_state_2) && (A != R.module_state_3))
 				//Module is not currently active
-				R.client.screen -= A
-		R.shown_robot_modules = FALSE
-		R.client.screen -= R.robot_modules_background
+				screenmob.client.screen -= A
+		shown_robot_modules = FALSE
+		screenmob.client.screen -= robot_modules_background
+
+/datum/hud/robot/persistent_inventory_update(mob/viewer)
+	if(!mymob)
+		return
+	var/mob/living/silicon/robot/R = mymob
+
+	var/mob/screenmob = viewer || R
+
+	var/held_items = list(R.module_state_1, R.module_state_2, R.module_state_3)
+	if(!screenmob.hud_used)
+		return
+	if(screenmob.hud_used.hud_shown)
+		for(var/i in 1 to length(held_items))
+			var/obj/item/I = held_items[i]
+			if(I)
+				switch(i)
+					if(1)
+						I.screen_loc = ui_inv1
+					if(2)
+						I.screen_loc = ui_inv2
+					if(3)
+						I.screen_loc = ui_inv3
+					else
+						return
+				screenmob.client.screen += I
+	else
+		for(var/obj/item/I in held_items)
+			screenmob.client.screen -= I

code/_onclick/hud/screen_objects.dm

@@ -367,6 +367,8 @@
 	screen_loc = ui_crafting
 
 /atom/movable/screen/craft/Click()
+	if(!isliving(usr))
+		return
 	var/mob/living/M = usr
 	M.OpenCraftingMenu()
 
@@ -396,24 +398,26 @@
 	object_overlays.Cut()
 
 /atom/movable/screen/inventory/proc/add_overlays()
-	var/mob/user = hud.mymob
+	var/mob/user = hud?.mymob
 
-	if(hud && user && slot_id)
-		var/obj/item/holding = user.get_active_hand()
+	if(!user || !slot_id || user != usr)
+		return
 
-		if(!holding || user.get_item_by_slot(slot_id))
-			return
+	var/obj/item/holding = user.get_active_hand()
 
-		var/image/item_overlay = image(holding)
-		item_overlay.alpha = 92
+	if(!holding || user.get_item_by_slot(slot_id))
+		return
 
-		if(!user.can_equip(holding, slot_id, disable_warning = TRUE))
-			item_overlay.color = "#ff0000"
-		else
-			item_overlay.color = "#00ff00"
+	var/image/item_overlay = image(holding)
+	item_overlay.alpha = 92
 
-		object_overlays += item_overlay
-		add_overlay(object_overlays)
+	if(!user.can_equip(holding, slot_id, TRUE))
+		item_overlay.color = "#ff0000"
+	else
+		item_overlay.color = "#00ff00"
+
+	object_overlays += item_overlay
+	add_overlay(object_overlays)
 
 /atom/movable/screen/inventory/MouseDrop(atom/over)
 	cut_overlay(object_overlays)