From Xojo Documentation

Property (As Integer )
aRealbasic.Size.Width = newIntegerValue
IntegerValue = aRealbasic.Size.Width

New in 2011r2

Supported for all project types and targets.

The width of the object, in pixels.

Sample Code

This example increases the height and width of the Size object.

Dim rectSize As New Realbasic.Size(100, 75)
rectSize.Height = 150
rectSize.Width = 200