First polish pass

code/modules/reagents/chemistry/machinery/chem_dispenser.dm

@@ -153,7 +153,6 @@
 /obj/machinery/chem_dispenser/tgui_data(mob/user)
 	var/data[0]
 
-	data["hasPower"] = !(stat & NOPOWER)
 	data["amount"] = amount
 	data["energy"] = cell.charge ? cell.charge * powerefficiency : "0" //To prevent NaN in the UI.
 	data["maxEnergy"] = cell.maxcharge * powerefficiency
@@ -187,51 +186,49 @@
 	if(..())
 		return
 
+	. = TRUE
 	switch(actions)
 		if("amount")
-			amount = clamp(round(text2num(params["amount"]), 1), 0, 100) // round to nearest 1 and clamp to 0 - 100
-			. = TRUE
+			amount = clamp(round(text2num(params["amount"]), 1), 0, 50) // round to nearest 1 and clamp to 0 - 50
 		if("dispense")
 			if(!is_operational() || QDELETED(cell))
 				return
-			if(beaker && dispensable_reagents.Find(params["reagent"]))
-				var/datum/reagents/R = beaker.reagents
-				var/free = R.maximum_volume - R.total_volume
-				var/actual = min(amount, (cell.charge * powerefficiency) * 10, free)
-
-				if(!cell.use(actual / powerefficiency))
-					atom_say("Not enough energy to complete operation!")
-					return
-
-				R.add_reagent(params["reagent"], actual)
-				overlays.Cut()
-				if(!icon_beaker)
-					icon_beaker = image('icons/obj/chemical.dmi', src, "disp_beaker") //randomize beaker overlay position.
-				icon_beaker.pixel_x = rand(-10, 5)
-				overlays += icon_beaker
-			. = TRUE
+			if(!beaker || !dispensable_reagents.Find(params["reagent"]))
+				return
+			var/datum/reagents/R = beaker.reagents
+			var/free = R.maximum_volume - R.total_volume
+			var/actual = min(amount, (cell.charge * powerefficiency) * 10, free)
+			if(!cell.use(actual / powerefficiency))
+				atom_say("Not enough energy to complete operation!")
+				return
+			R.add_reagent(params["reagent"], actual)
+			overlays.Cut()
+			if(!icon_beaker)
+				icon_beaker = mutable_appearance('icons/obj/chemical.dmi', "disp_beaker") //randomize beaker overlay position.
+			icon_beaker.pixel_x = rand(-10, 5)
+			overlays += icon_beaker
 		if("remove")
-			if(beaker && params["amount"])
-				var/amount = text2num(params["amount"])
-				if(isnum(amount) && (amount > 0))
-					var/datum/reagents/R = beaker.reagents
-					var/id = params["reagent"]
-					R.remove_reagent(id, amount)
-				else if(isnum(amount) && (amount == -1)) //Isolate instead
-					var/datum/reagents/R = beaker.reagents
-					var/id = params["reagent"]
-					R.isolate_reagent(id)
-			. = TRUE
+			var/amount = text2num(params["amount"])
+			if(!beaker || !amount)
+				return
+			var/datum/reagents/R = beaker.reagents
+			var/id = params["reagent"]
+			if(amount > 0)
+				R.remove_reagent(id, amount)
+			else if(amount == -1) //Isolate instead
+				R.isolate_reagent(id)
 		if("ejectBeaker")
-			if(beaker)
-				beaker.forceMove(loc)
-				if(Adjacent(usr) && !issilicon(usr))
-					usr.put_in_hands(beaker)
-				beaker = null
-				overlays.Cut()
-			. = TRUE
-	if(.)
-		add_fingerprint(usr)
+			if(!beaker)
+				return
+			beaker.forceMove(loc)
+			if(Adjacent(usr) && !issilicon(usr))
+				usr.put_in_hands(beaker)
+			beaker = null
+			overlays.Cut()
+		else
+			return FALSE
+
+	add_fingerprint(usr)
 
 /obj/machinery/chem_dispenser/attackby(obj/item/I, mob/user, params)
 	if(exchange_parts(user, I))
@@ -257,7 +254,7 @@
 		to_chat(user, "<span class='notice'>You set [I] on the machine.</span>")
 		SStgui.update_uis(src) // update all UIs attached to src
 		if(!icon_beaker)
-			icon_beaker = image('icons/obj/chemical.dmi', src, "disp_beaker") //randomize beaker overlay position.
+			icon_beaker = mutable_appearance('icons/obj/chemical.dmi', "disp_beaker") //randomize beaker overlay position.
 		icon_beaker.pixel_x = rand(-10, 5)
 		overlays += icon_beaker
 		return

code/modules/reagents/chemistry/machinery/chem_heater.dm

@@ -41,6 +41,7 @@
 		beaker = null
 		icon_state = "mixer0b"
 		on = FALSE
+		SStgui.update_uis(src)
 
 /obj/machinery/chem_heater/power_change()
 	if(powered())
@@ -63,6 +64,7 @@
 			I.forceMove(src)
 			to_chat(user, "<span class='notice'>You add the beaker to the machine!</span>")
 			icon_state = "mixer1b"
+			SStgui.update_uis(src)
 			return
 
 	if(exchange_parts(user, I))
@@ -100,36 +102,29 @@
 	if(..())
 		return
 
+	. = TRUE
 	switch(action)
 		if("toggle_on")
 			on = !on
-			return TRUE
 		if("adjust_temperature")
-			var/target = params["target"]
-			if(text2num(target) != null)
-				target = text2num(target)
-				. = TRUE
-			if(.)
-				desired_temp = clamp(target, 0, 1000)
+			desired_temp = clamp(text2num(params["target"]), 0, 1000)
 		if("eject_beaker")
 			eject_beaker(usr)
-			return TRUE
+		else
+			return FALSE
 
-/obj/machinery/chem_heater/tgui_interact(mob/user, ui_key = "main", datum/tgui/ui = null, force_open = 0, datum/tgui/master_ui = null, datum/tgui_state/state = GLOB.tgui_default_state)
+/obj/machinery/chem_heater/tgui_interact(mob/user, ui_key = "main", datum/tgui/ui = null, force_open = FALSE, datum/tgui/master_ui = null, datum/tgui_state/state = GLOB.tgui_default_state)
 	if(user.stat || user.restrained())
 		return
 
 	ui = SStgui.try_update_ui(user, src, ui_key, ui, force_open)
 	if(!ui)
-		ui = new(user, src, ui_key, "ChemHeater", name, 350, 270, master_ui, state)
+		ui = new(user, src, ui_key, "ChemHeater", "Chemical Heater", 350, 270, master_ui, state)
 		ui.open()
-		ui.set_autoupdate(TRUE)
 
 /obj/machinery/chem_heater/tgui_data(mob/user)
 	var/data[0]
 
-	data["hasPower"] = !(stat & NOPOWER)
-
 	data["targetTemp"] = desired_temp
 	data["isActive"] = on
 	data["isBeakerLoaded"] = beaker ? 1 : 0

code/modules/reagents/chemistry/machinery/chem_master.dm

@@ -181,7 +181,7 @@
 			playsound(loc, 'sound/goonstation/machines/printer_dotmatrix.ogg', 50, 1)
 
 			var/obj/item/paper/P = new /obj/item/paper(loc)
-			P.info = "<CENTER><B>Chemical Analysis</B></CENTER><BR>"
+			P.info = "<center><b>Chemical Analysis</b></center><br>"
 			P.info += "<b>Time of analysis:</b> [station_time_timestamp()]<br><br>"
 			P.info += "<b>Chemical name:</b> [R.name]<br>"
 			if(istype(R, /datum/reagent/blood))
@@ -395,8 +395,6 @@
 					tgui_modal_bento(src, id, "Please select the new style for bottles:", null, arguments, bottlesprite, bottle_styles_png)
 				else
 					return FALSE
-		if(TGUI_MODAL_DELEGATE)
-			// Do something after successful delegate call
 		if(TGUI_MODAL_ANSWER)
 			var/answer = params["answer"]
 			switch(id)
@@ -520,8 +518,6 @@
 					bottlesprite = new_sprite
 				else
 					return FALSE
-		if(TGUI_MODAL_CLOSE)
-			//
 		else
 			return FALSE