Added ui.RefreshEvent.

- Refresh signal is now propagated to controls.

ui/allg5ui/renderer.go

@@ -67,7 +67,7 @@ func (r *Renderer) PushEvents(t ui.EventTarget, wait bool) {
 		case *allg5.MouseMoveEvent:
 			t.Handle(&ui.MouseMoveEvent{MouseEvent: mouseEvent(e.MouseEvent), MouseWheel: float32(e.DeltaZ)})
 		case *allg5.UserEvent:
-			// used to unblock the wait for events.
+			t.Handle(&ui.RefreshEvent{EventBase: eventBase(e)})
 		}
 		ev = r.eq.Get()
 	}

ui/event.go

@@ -54,3 +54,7 @@ type MouseMoveEvent struct {
 	MouseEvent
 	MouseWheel float32
 }
+
+type RefreshEvent struct {
+	EventBase
+}