[rapps_new] in windowed mode does not allow resizing details section

reactOS 0.4.5RC1
Resizing the details section with mouse works in maximized mode, but not in windowed mode, see rapps_new.webm
No LogOutput is generated upon trying.

this is reported towards ancient rapps_new, which is now named rapps.
I have not double-checked how rapps_old would behave, but do not remember ever being bothered by this earlier.