Using Xfwm from the master branch (4.13.1 + three commits, be929b2a (common: Convert monitor geometry to device geometry)), the window switch overlay(?) is position in the right-bottom corner with window scaling set to *2x*.
This might be related to bug 14566.
Closing as a dupe of bug 14931 even though this bug was filed before bug 14931, but the latter has a patch
*** This bug has been marked as a duplicate of bug 14931 ***