23:16:19equwalknobo: Your question might be better phrased as "does CLX have support for listening to meta keys press and release?"
23:19:35equwalI'm thinking xlib:event-mask-class is the right place to be looking
23:29:35equwalFrom the texinfo manual clx.texinfo: Note that @var{:key-press} and @var{:key-release} are generated for all keys, even those mapped to modifiers.