Specifies the width and height of the specified background.Syntax:
set the backSize of <group> to <width>, <height>
set the backSize of group "Nav Bar" to 160,20
The first item of the backSize is the width of the group in pixels. The second item is the height of the group in pixels.
If you change the backSize of a group, the position of its top left corner remains unchanged.
This property is included in LiveCode for compatibility with imported SuperCard projects.