Contains the top coordinate of the form that is visible in the viewport. Read-only at design time and run time.
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 top coordinate of the form is determined by the form's ScaleMode property setting вЂ“ pixels (the default) or foxels.