Allow tab key to be used for shortcuts

scene/main/viewport.cpp

@@ -2291,12 +2291,12 @@ void Viewport::_gui_input_event(Ref<InputEvent> p_event) {
 		if (from && p_event->is_pressed()) {
 			Control *next = NULL;
 
-			if (p_event->is_action_pressed("ui_focus_next")) {
+			if (!mods && p_event->is_action_pressed("ui_focus_next")) {
 
 				next = from->find_next_valid_focus();
 			}
 
-			if (p_event->is_action_pressed("ui_focus_prev")) {
+			if (!mods && p_event->is_action_pressed("ui_focus_prev")) {
 
 				next = from->find_prev_valid_focus();
 			}