Replace opacity = X with set_opacity(X) so that the lighting system can update propertly.

code/game/objects/effects/chem/chemsmoke.dm

@@ -162,9 +162,9 @@
 	smoke.pixel_x = -32 + rand(-8, 8)
 	smoke.pixel_y = -32 + rand(-8, 8)
 	walk_to(smoke, T)
-	smoke.opacity = 1		//switching opacity on after the smoke has spawned, and then
+	smoke.set_opacity(1)		//switching opacity on after the smoke has spawned, and then
 	sleep(150+rand(0,20))	// turning it off before it is deleted results in cleaner
-	smoke.opacity = 0		// lighting and view range updates
+	smoke.set_opacity(0)		// lighting and view range updates
 	fadeOut(smoke)
 	qdel(src)
 

code/game/objects/structures/curtains.dm

@@ -27,7 +27,7 @@
 	..()
 
 /obj/structure/curtain/proc/toggle()
-	opacity = !opacity
+	set_opacity(!opacity)
 	if(opacity)
 		icon_state = "closed"
 		layer = SHOWER_CLOSED_LAYER

code/game/objects/structures/simple_doors.dm

@@ -32,9 +32,9 @@
 	name = "[material.display_name] door"
 	color = material.icon_colour
 	if(material.opacity < 0.5)
-		opacity = 0
+		set_opacity(0)
 	else
-		opacity = 1
+		set_opacity(1)
 	if(material.products_need_process())
 		processing_objects |= src
 	update_nearby_tiles(need_rebuild=1)
@@ -99,7 +99,7 @@
 	flick("[material.door_icon_base]opening",src)
 	sleep(10)
 	density = 0
-	opacity = 0
+	set_opacity(0)
 	state = 1
 	update_icon()
 	isSwitchingStates = 0
@@ -111,7 +111,7 @@
 	flick("[material.door_icon_base]closing",src)
 	sleep(10)
 	density = 1
-	opacity = 1
+	set_opacity(1)
 	state = 0
 	update_icon()
 	isSwitchingStates = 0

code/game/turfs/simulated/wall_attacks.dm

@@ -11,7 +11,7 @@
 		update_icon()
 		set_light(0)
 		src.blocks_air = 0
-		src.opacity = 0
+		set_opacity(0)
 		for(var/turf/simulated/turf in loc)
 			air_master.mark_for_update(turf)
 	else
@@ -21,7 +21,7 @@
 		update_icon()
 		set_light(1)
 		src.blocks_air = 1
-		src.opacity = 1
+		set_opacity(1)
 		for(var/turf/simulated/turf in loc)
 			air_master.mark_for_update(turf)
 

code/modules/hydroponics/spreading/spreading.dm

@@ -192,7 +192,7 @@
 
 	if(growth>2 && growth == max_growth)
 		layer = 5
-		opacity = 1
+		set_opacity(1)
 		if(!isnull(seed.chems["woodpulp"]))
 			density = 1
 	else

code/modules/random_map/drop/droppod_doors.dm

@@ -70,11 +70,11 @@
 
 	// Create a decorative ramp bottom and flatten out our current ramp.
 	density = 0
-	opacity = 0
+	set_opacity(0)
 	icon_state = "ramptop"
 	var/obj/structure/droppod_door/door_bottom = new(T)
 	door_bottom.deployed = 1
 	door_bottom.density = 0
-	door_bottom.opacity = 0
+	door_bottom.set_opacity(0)
 	door_bottom.dir = src.dir
 	door_bottom.icon_state = "rampbottom"

code/modules/shieldgen/emergency_shield.dm

@@ -54,8 +54,8 @@
 	playsound(src.loc, 'sound/effects/EMPulse.ogg', 75, 1)
 
 	check_failure()
-	opacity = 1
+	set_opacity(1)
-	spawn(20) if(src) opacity = 0
+	spawn(20) if(!deleted(src)) set_opacity(0)
 
 	..()
 
@@ -63,8 +63,8 @@
 	health -= Proj.get_structure_damage()
 	..()
 	check_failure()
-	opacity = 1
+	set_opacity(1)
-	spawn(20) if(src) opacity = 0
+	spawn(20) if(!deleted(src)) set_opacity(0)
 
 /obj/machinery/shield/ex_act(severity)
 	switch(severity)
@@ -113,8 +113,8 @@
 	check_failure()
 
 	//The shield becomes dense to absorb the blow.. purely asthetic.
-	opacity = 1
+	set_opacity(1)
-	spawn(20) if(src) opacity = 0
+	spawn(20) if(!deleted(src)) set_opacity(0)
 
 	..()
 	return