put some shades under windows

[colben]

Could you please put some shades around borders of windows , which can make windows more obvious ...

[toshjp]

I would like to suggest something to the same effect. Since no bottom border is drawn, when, for example, two windows with the same background colour neatly overlap and only part of the window that is behind can be seen under the bottom of the foremost window, you cannot tell where the foremost window ends. I suppose there should be a slim border at the bottom of the window so you can easily tell where these windows actually overlap.