Converting (10,10) to FileDialog coordinates, the test fails for me on both Windows 7 and 10. It reports some random gray color. Adding some synchronization and a small delay on the main thread, I finally see white (on Windows 10); positioning Robot at that converted point I see it on a wide frame margin to the left of the red icon.

I think the locationOnTheScreen for the FileDialog reports correct coordinates on Window, so there should be something more than 10: perhaps several attempts starting from 10?