bug#5721: Feature request: Function that returns absolute coordinates

[martin rudalics]

> Also the size of the decoration doesn't really matter, as long as we can
> figure out the difference between the absolute frame position and the
> start of the edit window.

But the decorations are part of this difference.  They are between the
absolute frame position and the position of the frame's root window.

> P.S.: I tried the patch on a bare --with-x-toolkit=no build and it seems
> to give the correct values.

How to you establish that a value is "correct"?

martin