Syntax

[the] rectangle of <buttonOrFieldOrStack>

set the rectangle of field "Popup" to left: 20, top: 20, right: 492, bottom: 322

Explanation

The rectangle property describes the position and size of an object, by specifying the distance of the top, left, bottom and right edges of the box surrounding the object from the top left corner of the stack (or in case of a stack, of the menu bar).