patch 9.1.0063: GTK code can be improved

Problem:  GTK code can be improved
Solution: Improve GTK code for initial Wayland support
          (lilydjwg)

related: #9639

Signed-off-by: lilydjwg <lilydjwg@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/clipboard.c b/src/clipboard.c
index d80699b..8b9850e 100644
--- a/src/clipboard.c
+++ b/src/clipboard.c
@@ -1334,7 +1334,8 @@
 #ifdef FEAT_GUI_GTK
 	if (gui.in_use)
 	{
-	    gui_gtk_set_selection_targets();
+	    gui_gtk_set_selection_targets((GdkAtom)GDK_SELECTION_PRIMARY);
+	    gui_gtk_set_selection_targets((GdkAtom)clip_plus.gtk_sel_atom);
 	    gui_gtk_set_dnd_targets();
 	}
 #endif