Dragging: Don't allow using non-interactive items by dropping them

Was broken in commit f704006.

Fixes: issue #1011

CHANGELOG

@@ -1,6 +1,10 @@
 
 = Arx Libertatis 1.2.1  (TBD) =
 
+Gameplay:
+
+* Fixed being able to use items multiple times by dropping them on the player book (bug #1011)
+
 Audio:
 
 * Fixed missing death screams for most NPCs (bug #1579)

src/gui/Dragging.cpp

@@ -218,7 +218,7 @@ void updateDraggedEntity() {
 		return;
 	}
 	if(ARX_INTERFACE_MouseInBook()) {
-		if(drop && g_playerBook.currentPage() == BOOKMODE_STATS) {
+		if(drop && g_playerBook.currentPage() == BOOKMODE_STATS && (entity->gameFlags & GFLAG_INTERACTIVITY)) {
 			SendIOScriptEvent(entities.player(), entity, SM_INVENTORYUSE);
 			COMBINE = NULL;
 		}