Picker outside screen

I have a staticFormItem with a customized picker. I move the picker to the icon position using picker.moveTo(iconRect.getLeft(), iconRect.getTop());. This works fine, but when the formItem is near the right corner of the screen, a part of the picker is not visible (outside the screen). How is it possible to detect this to move the picker to a better position in this case?
Same for the bottom corner of the screen.

Using smartGwt 4.1p.