scrollbar drawing issues within a listview of 'click n type virtual keyboard' msi setup

Reproduction steps

• start msi setup of "click n type virtual keyboard 3.03.412" from rapps
• click the button to view "disk usage" when the msi setup requests the path to install
• in the resulting listview try to resize the columns to make a scrollbar appear

Expected result
it shall always properly paint all areas of the scrollbar
2k3sp2_scrollbar_ok.webm

Observed result
Sometimes drawing issues are exposed
0.4.14-RC-96-g08352ec_cntSetup_scrollbar.webm
0.4.14-RC-96-g08352ec_cntSetup_scrollbar.log (nothing gets logged when intereracting with that listview like that)