bad tooltip position

Steps to reproduce:
1. place a button, centered at the bottom of the application
2. add long tooltip to it (just use the tooltip attribute inline)
3. run

Actual Results:
the tooltip covers the button and the button is not visible.

Expected Results:
the tooltip manager should recognize the button location and the application and re-calculate the tooltip position so it will not hide the button. This looks worst when there are more than one button, and the tooltip hides them all

Workaround (if any):