When you disable compositing if you take a screenshot of the area, the system freezes. The keyboard is not responding.
xfwm4 version 4.13.1
I'm using both xfwm4 and screenshooter from git master and cannot reproduce, works fine with compositing disabled. Are you able to compile with debugging info and provide a backtrace? It is as easy as: git clone https://git.xfce.org/apps/xfce4-screenshooter cd xfce4-screenshooter ./autogen.sh --prefix=/usr --enable-debug=yes make src/xfce4-screenshooter -r
Now I have a stable xfce4 + xwm 4-devel, but there is no problem with git screenshooter. Apparently the problem lies in another package or in devel-xfce4 as a whole.
I'm closing as invalid since it seems to be caused by another component. If you find any helpful evidence please file a bug to the appropriate component, or reopen this bug if think screenshooter is indeed causing the system to freeze.