@mkormendy You have great attention to detail. That is good!
I noticed this problem after releasing the version. It is supposed to look like in your demo screenshot. But I realized that this is affected by system settings: System Preferences -> General -> Show scroll bars (and selecting different options behaves differently if you have external mouse connected or not).
Right now I draw label frame computed from cell frame. I have to switch that code and determine actual frame of Finder selection instead. Cell frame is affected by that system option and makes labels look differently as you correctly pointed out.