What do you mean with "windowed" mode? When I switch mediathekview from fullscreen to a window and resize it, no redraw happens and the problem persists.
I forwarded the bug to upstream. I use xmonad since many years with many different programs using many different toolkits. Mediathekview is the first program I remember having rendering problems. Please keep this bug open for the moment and lets wait for upstream. Thank you.
