Saline drips have a valid icon again, Update Icon Blocker modernization

code/datums/elements/update_icon_blocker.dm

@@ -1,12 +1,22 @@
 //Prevents calling anything in update_icon() like update_icon_state() or update_overlays()
 
-/datum/element/update_icon_blocker/Attach(datum/target)
+/datum/element/update_icon_blocker
+	element_flags = ELEMENT_BESPOKE
+	id_arg_index = 2
+
+	/// Set of COMSIG_ATOM_UPDATE_ICON to return. See [signals_atom_main.dm]
+	var/blocking_flags
+
+/datum/element/update_icon_blocker/Attach(datum/target, blocking_flags = COMSIG_ATOM_NO_UPDATE_ICON_STATE | COMSIG_ATOM_NO_UPDATE_OVERLAYS)
 	. = ..()
-	if(!istype(target, /atom))
+	if(!isatom(target))
 		return ELEMENT_INCOMPATIBLE
+	if(!blocking_flags)
+		CRASH("Attempted to block icon updates with a null blocking_flags argument. Why?")
+	src.blocking_flags = blocking_flags
 	RegisterSignal(target, COMSIG_ATOM_UPDATE_ICON, PROC_REF(block_update_icon))
 
 /datum/element/update_icon_blocker/proc/block_update_icon()
 	SIGNAL_HANDLER
 
-	return COMSIG_ATOM_NO_UPDATE_ICON_STATE | COMSIG_ATOM_NO_UPDATE_OVERLAYS
+	return blocking_flags

code/game/machinery/iv_drip.dm

@@ -24,6 +24,8 @@
 	var/obj/item/reagent_container
 	///Set false to block beaker use and instead use an internal reagent holder
 	var/use_internal_storage = FALSE
+	///If use_internal_storage is true, this is the created volume of the container
+	var/internal_storage_volume = 100
 	///Typecache of containers we accept
 	var/static/list/drip_containers = typecacheof(list(
 		/obj/item/reagent_containers/blood,
@@ -38,7 +40,7 @@
 	. = ..()
 	update_appearance()
 	if(use_internal_storage)
-		create_reagents(100, TRANSPARENT)
+		create_reagents(internal_storage_volume, TRANSPARENT)
 	interaction_flags_machine |= INTERACT_MACHINE_OFFLINE
 
 /obj/machinery/iv_drip/Destroy()
@@ -312,13 +314,16 @@
 	desc = "An all-you-can-drip saline canister designed to supply a hospital without running out, with a scary looking pump rigged to inject saline into containers, but filling people directly might be a bad idea."
 	icon_state = "saline"
 	base_icon_state = "saline"
+	use_internal_storage = TRUE
+	internal_storage_volume = 5000
 	density = TRUE
 	inject_only = TRUE
 
 /obj/machinery/iv_drip/saline/Initialize(mapload)
+	AddElement(/datum/element/update_icon_blocker, COMSIG_ATOM_NO_UPDATE_OVERLAYS)
 	. = ..()
-	reagent_container = new /obj/item/reagent_containers/glass/saline(src)
-	AddElement(/datum/element/update_icon_blocker)
+	// Parent call creates our container. Fill it up to max.
+	reagents.add_reagent(/datum/reagent/medicine/saline_glucose, internal_storage_volume)
 
 /obj/machinery/iv_drip/saline/eject_beaker()
 	return

code/modules/reagents/reagent_containers/glass.dm

@@ -385,8 +385,3 @@
 		grinded = I
 		return
 	to_chat(user, span_warning("You can't grind this!"))
-
-/obj/item/reagent_containers/glass/saline
-	name = "saline canister"
-	volume = 5000
-	list_reagents = list(/datum/reagent/medicine/saline_glucose = 5000)