patch 8.2.2622: GTK: error when starting up and -geometry is given

Problem:    GTK: error when starting up and -geometry is given. (Dominique
            Pellé)
Solution:   Use another function to get the monitor if the window has not been
            created yet. (closes #7978)
diff --git a/src/gui_beval.c b/src/gui_beval.c
index 57122ff..10478c6 100644
--- a/src/gui_beval.c
+++ b/src/gui_beval.c
@@ -920,7 +920,7 @@
 	screen = gtk_widget_get_screen(beval->target);
 	gtk_window_set_screen(GTK_WINDOW(beval->balloonShell), screen);
 # endif
-	gui_gtk_get_screen_geom_of_win(beval->target,
+	gui_gtk_get_screen_geom_of_win(beval->target, 0, 0,
 				    &screen_x, &screen_y, &screen_w, &screen_h);
 # if !GTK_CHECK_VERSION(3,0,0)
 	gtk_widget_ensure_style(beval->balloonShell);