Hi,
while I'm not the maintainer for this package in Debian and thus I'm to lazy to file single bug reports with pull requests I'd like to drop a note here that you can find some patches inside the Debian packaging git which apply to the current commit here in this repository. It might make sense to incorporate these.
BTW, it might make perfectly sense to tag a new upstream version here.
Thanks a lot for salvaging wmctrl here in Github.
Kind regards, Andreas.