Why causes the change of the Location the change of the size

[MarkPhB]

When i just change the location of a form with an overridden show-methode and theange of the size form is hidden while i change the location, the size will be changed too :mad: like

public void Show( IWin32Window owner, int positionX, int positionY ) {
  if( this.Visible == false ) {
    this.SetDesktopLocation( positionX, positionY ); // Here is the Size W=210,H=40
    this.Size = this.RestoreBounds.Size; // After this line the Size W=205, H=16
    this.BringToFront();
    this.Show( owner );
  }
  else {
    this.Activate();
  }
}