The Windows application and Companion Mode app quite desperately need at least a 1-pixel border around them. Visually, it is far too difficult to find the top of the window quickly. Not everyone uses a dark theme and having a white application bleed over another white application without any visual key is less than ideal. Attached is a screencap of the Fellow application over this very web page. As you can (not) see, the edge of the application isn't apparent. I'm hard-pressed to find another Windows application that doesn't have at least a 1-pixel border with either a complementary or contrasting color to the application.