window-list: Invalid current mode selected in Preferences

It seems that gtk+ resets the active radio whenever a new radio button
is added into the group, thus rather restore the current mode after
the group is fully populated.

!119
3 jobs for master in 1 minute and 34 seconds
Status Job ID Name Coverage
  Review
passed #675407
eslint

00:00:41

passed #675406
js_check

00:00:36

 
  Build
passed #675408
build-bundles

00:00:52