def mouse_up_at(self,locator,coordString):
self.do_command("<STR_LIT>", [locator,coordString,])<EOL>
Simulates the event that occurs when the user releases the mouse button (i.e., stops
holding the button down) at the specified location.

'locator' is an element locator
'coordString' is specifies the x,y position (i.e. - 10,20) of the mouse      event relative to the element returned by the locator.