diff -upr uim-1.8.8.org/gtk2/immodule/caret-state-indicator.c uim-1.8.8/gtk2/immodule/caret-state-indicator.c
--- uim-1.8.8.org/gtk2/immodule/caret-state-indicator.c	2020-08-08 17:29:37.000000000 +0900
+++ uim-1.8.8/gtk2/immodule/caret-state-indicator.c	2020-08-08 17:21:29.000000000 +0900
@@ -135,6 +135,10 @@ caret_state_indicator_new(void)
   GList *label_list = NULL, *frame_list = NULL;
 
   window = gtk_window_new(GTK_WINDOW_POPUP);
+#if GTK_CHECK_VERSION(3, 0, 0)		/* Patched by G-HAL, 2020/08/08 */
+  gtk_style_context_add_class(gtk_widget_get_style_context(window), GTK_STYLE_CLASS_POPUP);		/* Patched by G-HAL, 2018/10/20 */
+  gtk_widget_set_name(window, "uim");	/* Patched by G-HAL, 2020/08/08 */
+#endif
   label  = gtk_label_new("");
   frame = gtk_frame_new(NULL);
   gtk_container_add(GTK_CONTAINER(frame), label);