Wayland: Copy to clipboard does not work

Under Wayland gdk_display_supports_clipboard_persistence always return false (source here). Even if copying to clipboard is not guarded by that function, it simply doesn't work.

My theory is that a window needs to be displayed at the time gtk_clipboard_set_image is called and that it may take a while for the data transfer to finish. With a quick and dirty hack I could make it work only once, apparently not reliably. Or since gtk_clipboard_store is basically no-op under Wayland, the data is lost after the application finishes.

@Tamaranch any idea what could be the issue here with gtk/wayland?