ViewPortWidth Property
Contains the viewport width for a form. Read-only at design time and run time.
Object.ViewPortWidth
Remarks
Applies To: Form Object
The viewport is the rectangular area of a form displayed in the form's container. The form container controls the size of the viewport. If you change the size of a form's container, the viewport also changes size.
The unit of measurement for the viewport width is determined by the form's ScaleMode property setting – pixels (the default) or foxels.