adds click drag from storage into your hands

code/__DEFINES/dcs/signals/atom/signals_atom.dm

@@ -45,3 +45,9 @@
 
 ///When the transform or an atom is varedited through vv topic.
 #define COMSIG_ATOM_VV_MODIFY_TRANSFORM "atom_vv_modify_transform"
+
+/// Called when an atom has something mouse dropped on it, from /client/MouseDrop: (atom/dropped_on)
+#define COMSIG_ATOM_DROPPED_ON "atom_dropped_on"
+
+/// Called when an atom is mouse dropped on another atom, from /client/MouseDrop: (atom/dropped_onto)
+#define COMSIG_ATOM_DROP_ON "atom_drop_on"

code/_onclick/click_hold.dm

@@ -94,3 +94,12 @@
 
 	// Add the hovered atom to the trace
 	LAZYADD(mouse_trace_history, over_obj)
+
+/client/MouseDrop(datum/over_object, datum/src_location, over_location, src_control, over_control, params)
+	. = ..()
+
+	if(src_location)
+		SEND_SIGNAL(src_location, COMSIG_ATOM_DROPPED_ON, over_object, src)
+
+	if(over_object)
+		SEND_SIGNAL(over_object, COMSIG_ATOM_DROP_ON, src_location, src)

code/_onclick/hud/screen_objects.dm

@@ -30,6 +30,10 @@
 /atom/movable/screen/inventory
 	var/slot_id //The indentifier for the slot. It has nothing to do with ID cards.
 
+/atom/movable/screen/inventory/Initialize(mapload, ...)
+	. = ..()
+
+	RegisterSignal(src, COMSIG_ATOM_DROPPED_ON, PROC_REF(handle_dropped_on))
 
 /atom/movable/screen/close
 	name = "close"
@@ -325,6 +329,22 @@
 				return 1
 	return 0
 
+/atom/movable/screen/inventory/proc/handle_dropped_on(atom/dropped_on, atom/dropping, client/user)
+	SIGNAL_HANDLER
+
+	if(slot_id != WEAR_L_HAND && slot_id != WEAR_R_HAND)
+		return
+
+	if(!isstorage(dropping.loc))
+		return
+
+	if(!user.mob.Adjacent(dropping))
+		return
+
+	var/obj/item/storage/store = dropping.loc
+	store.remove_from_storage(dropping, get_turf(user.mob))
+	user.mob.put_in_active_hand(dropping)
+
 /atom/movable/screen/throw_catch
 	name = "throw/catch"
 	icon = 'icons/mob/hud/human_midnight.dmi'