Kills all visible clients that are unselected. That is, after running
killunsel, only the selected client will remain. The rest will not only be
not visible, but they will have been killed.
This is essentially equivalent in idea to :tabonly (albeit per-client, not per-"tab") in vim.
- dwm-killunsel-ceac8c91ff.diff (1.7k) (20170728)