Fix global redisplay not matching window updates

The global redisplay thread would block on a semaphore, which is
signaled by the per-window redisplay threads whenever the content of any
window changes. For example, the per-window redisplay thread is triggered
when its content twin_box_t is triggered by the event
TwinEventButtonDown. In this case, the corresponding window should also
be marked as active. To ensure proper display, we added the function
twin_window_show to indirectly update the damaged screen.

Signed-off-by: Wei-Hsin Yeh <weihsinyeh168@gmail.com>

Author: weihsinyeh

src/box.c

@@ -163,6 +163,7 @@ twin_dispatch_result_t _twin_box_dispatch(twin_widget_t *widget,
     case TwinEventConfigure:
         return _twin_box_configure(box);
     case TwinEventButtonDown:
+        twin_window_show(widget->window);
         box->button_down =
             _twin_box_xy_to_widget(box, event->u.pointer.x, event->u.pointer.y);
         if (box->button_down && box->button_down->want_focus)