use vte context menu setup
Branch: wip/context-menu
It's working, except that it causes an undebuggable crash in gtk (on X11) after the context menu has been shown a number of times (not reproducible in vte-2.91-gtk4):
Gdk:ERROR:../gdk/gdkkeys.c:463:gdk_keymap_get_cached_entries_for_keyval: assertion failed: (len <= 255)
Bail out! Gdk:ERROR:../gdk/gdkkeys.c:463:gdk_keymap_get_cached_entries_for_keyval: assertion failed: (len <= 255)