Graphical regions are often used as parents of other objects. For example, suppose you specify the following:

 

graphical region Panel size 200 300 at position 100 50

 

key Button at position 50 50 in Panel

    draw 100 100

 

Because the key named Button is defined as being in the graphical region named Panel, Button is the child of Panel. Panel is the parent, or the ancestor, of Button.

 

When a key is defined in this way, its coordinate positions are relative to the starting position of the graphical region. The starting position of Button is 50 50 within the Panel region, as shown in the following example: