Bug fix: Issue #46: Optionally mark override-redirect windows as active

Attempt to fix the transparency issue of Firefox and Chromium location
bar dropdown window by marking override_redirect windows as active. This
may not work completely and could have other side effects. Experimental.
Enable by using --mark-ovredir-focused.

compton.sample.conf

@@ -27,6 +27,7 @@ fade-out-step = 0.03
 
 # Other
 mark-wmwin-focused = true;
+mark-ovredir-focused = true;
 
 # Window type settings
 wintypes: