Node UI:

* Added Backdrop Panel inside the "Properties" area.
* Hard limit for the "zoom" value. Negative values doesn't make sense. 
* Added a missing notifier for the Node backdrop move operator.

source/blender/editors/space_node/node_edit.c

@@ -784,6 +784,8 @@ static int snode_bg_viewmove_modal(bContext *C, wmOperator *op, wmEvent *event)
 			
 			MEM_freeN(nvm);
 			op->customdata= NULL;
+            
+			WM_event_add_notifier(C, NC_SPACE|ND_SPACE_NODE, NULL);
 			
 			return OPERATOR_FINISHED;
 	}
@@ -831,6 +833,7 @@ void NODE_OT_backimage_move(wmOperatorType *ot)
 {
 	/* identifiers */
 	ot->name= "Background Image Move";
+	ot->description = "Move Node backdrop";
 	ot->idname= "NODE_OT_backimage_move";
 	
 	/* api callbacks */