Rocks and Diamonds setup from rapps, taskbar pane does not get active

Observed result
0.4.13-RC-46-gbb9997c_RnD_fails.webm
0.4.13-RC-46-gbb9997c_RnD_fails.log
The taskbars pane (button) of RocksNDiamonds setup from rapps erroneously does not get into pressed state when starting the app. As a consequence minimize/maximize-alternation invoked via taskbar pane later does not work properly.

This bug does happen with all of those:
0.4.13-RC-46-gbb9997c vanilla
0.4.13-RC-46-gbb9997c + explorer-workaround of DougLyons from CORE-16703 taskswnd_c_hack
0.4.13-RC-46-gbb9997c + patch of blueghost from CORE-16703 ntuser_focus2.patch
0.4.14-dev-1012-g820dbfc master head vanilla

I suspect the bug is in WIN32SS.

Expected result
2k3sp2_RnD_ok.webm does properly show the pressed pane and can even minimize/maximize-alternate when clicking the taskbar button repeatedly.