You should not assume that a window is located where it has just been programmatically positioned. Instead you should query the current position by
So if you wish to display CAPI interface windows W1 and W2 relative to each other. You should:
make-instanceor later by
The reason for this is that the window system may disallow certain positions (for example on the Mac OS X menu bar) therefore you cannot be certain of the position of W1 .
CAPI User Guide (Unix version) - 30 Aug 2011