Several functions are useful for getting properties of an existing graphics frame:
H Size
Returns the horizontal size of the graphics frame in pixels.
V Size
Returns the vertical size of the graphics frame in pixels.
X Origin
Returns the x-value for the left edge of the graphics frame.
X Range
Returns the distance from the left to right edges of a display box.
Y Origin
Returns the y-value for the bottom edge of the graphics frame.
Y Range
Returns the distance from the bottom to top edges of a display box.
In the following expressions, the first line calculates the right edge. The second line calculates the top edge.
Oval(
...,
rightEdge = X Origin() + X Range();
topEdge = Y Origin() + Y Range();
);