Do not cancel event if no need to cancel it. Fixes problem with GUI in 3D.

scene/main/scene_tree.cpp

@@ -418,12 +418,12 @@ void SceneTree::input_event(const Ref<InputEvent> &p_event) {
 
 	if (!input_handled) {
 		call_group_flags(GROUP_CALL_REALTIME, "_viewports", "_vp_unhandled_input", ev); //special one for GUI, as controls use their own process check
-		input_handled = true;
 		_flush_ugc();
+		//		input_handled = true; - no reason to set this as handled
 		root_lock--;
 		//MessageQueue::get_singleton()->flush(); //flushing here causes UI and other places slowness
 	} else {
-		input_handled = true;
+		//		input_handled = true; - no reason to set this as handled
 		root_lock--;
 	}