I think the above code works only for winforms. Try below in code activity
Arguments:
pt - System.Drawing.Point
pt= New Point(Cursor.Position.X - 50, Cursor.Position.Y - 50)
Cursor.Position = pt
For size part, something like this should work
size = New System.Drawing.Size(10, 10)
pt= New System.Drawing.Point(Cursor.Position.X + 50, Cursor.Position.Y + 50)
Cursor.Position = pt
Cursor.Clip = New Rectangle(pt,size)