There's a feature on Windows that I rely on, I always have Medium set.

Windows 7 64-bit

Windows Setting - http://i.imgur.com/ThLuKTr.jpg 

UI - http://i.imgur.com/Xw9Tfoc.jpg 

RD Tabs is full of bugs and the UI looks terrible when in Medium mode. I can only switch to Smaller (100%) if I log out first, which I do not wish to do. Would love to switch over from Remote Desktop Connection Manager v2.2 if this bug is resolved.

RD Tabs will properly support DPI scaling in the next release. Sorry about that.