Probably a result of #990. For example, the "decorations" attribute does get set properly, but it doesn't get exported. It looks like the gobject property stuff doesn't work as expected.
Should be fixed in r11933. This was caused by us overwriting the value we find from the motif wm hints with the default value rather than a gobject issue (not that there aren't issues with gobject still..)
Should be backported.
this ticket has been moved to: https://github.com/Xpra-org/xpra/issues/1120