WINGs/wayland: flush display after surface commit for immediate updates

Without an explicit wl_display_flush after wl_surface_commit, protocol
requests were buffered until the next event loop iteration. This caused
visual updates (like the icon position preview in WPrefs) to appear one
interaction behind.

WINGs/wclient_wl.c

@@ -403,6 +403,8 @@ wl_client_toplevel_commit_locked(WLClientToplevel *top)
     wl_surface_damage_buffer(top->surface, 0, 0,
                              top->buf->width, top->buf->height);
     wl_surface_commit(top->surface);
+    if (top->ctx && top->ctx->display)
+        wl_display_flush(top->ctx->display);
     top->buf->busy = 1;
     top->mapped = 1;
 }