Affected application: tilda, a dropdown terminal. When launched, the application shows but fails to capture accept keyboard entries. Reverting the commit (quoted below) in master solves the issue.
Tested application: https://github.com/lanoxx/tilda/archive/tilda-1.5.2.tar.gz
Related commit: http://git.fluxbox.org/fluxbox.git/commit/?h=prep/release-1.4.0&id=e85cf490355346d89f4f758d3193ed7199280793