Remove distro folder.
Add return to gboolean function

Closes #134
https://github.com/mate-desktop/mate-panel/issues/134
Fix not expanded applets list in GTK3 addto dialog
wncklet: Fit window list size with GTK3
Revert "Correct wnck/gtk3 check."

This reverts commit a2b1af54a24b93766f5e2ed4a216637dc510ec47.
Revert "Fixed the WNCK_CHECK_VERSION calls to only be used when GTK is version"

This reverts commit 428e32cd0f3f2df0cbd4e859304f0935a11612bc.
Check if WNCK_CHECK_VERSION is defined.

In older version of libwnck WNCK_CHECK_VERSION does not exist.