Look, I'm very interested in knowing how youre are doing this. I have tryied many ways and been only able to get the close action on enter not on click,(when you click the window looses focus so it doesent work)
The best way I got to doit is ussing STbangs module and call:!STCloseCurWindow fron a label on enter ( it does not work on click)
If you can get this done on click It'll be interesting to know how you doit.

Suggestions:
Youre Idea Is good but....
If you set youre desktop area to "0,9,0,-28" and make an xlabel 29 height allwaysontop across the top
now there is were you put your close button and..........,
there is no more titlebar for maximized windows.
now if yore are ussing taskbar for youre regular taskbar you can load tasks and hook that to youre new titlebar showing only active.
that will give you an effect you might whant.
If you are interested on managing windows I suggest you try wndman and lsplus.
literunner and kidnap are good mods but wndman is just superior IMO.
well good luck.