http://bugs.winehq.org/show_bug.cgi?id=58606
--- Comment #6 from Stian Low wineryyyyy@gmail.com --- (In reply to Stian Low from comment #5)
I just reconfirmed with a fresh rebuild and clean ~/.wine that the dropdowns indeed are working for me.
Actually I may have gotten lucky and it was reproduced with another test.
Upon first opening I clicked the dropdown for Pigments multiple times and it wouldn't open. But after moving the windows, the dropdown started working again when clicked.
Can you test if moving the window then clicking on the dropdown fixes it?