SetScale allows the user to change the scale property without resizing the frame and upsetting the layout.
The standard Frame Object dialog in MapInfo Pro lets the user change the scale property of a Map Frame by typing a new number into the Scale-on-Paper text box. Unfortunately MapInfo then sets the new scale by changing the frame-width-paper-units term while keeping constant the zoom-width-dist-units term. The map coverage is preserved but the frame is resized, possibly even expanding to a size exceeding the printable area of the page. The layout must then be re-worked manually.
SetScale allows the user to change the scale property without resizing the frame and upsetting the layout. It does this by calculating a new zoom-width-dist-units term while keeping constant the frame-width-paper-units term and then changing the zoom of the underlying map window.