BalloonWindow Library for .NET

If the BalloonWindow is attached to a control, and the
form with that control is moved, the first repaint of the
BalloonWindow draws it in the middle of the screen.

This is due to the __targetControlRect variable in
TrackLayoutHandler not being initialized the first time.

I've fixed it in my source code by adding the following
code to the TargetControl property handler:

if(MoveWithTarget)
{
if(value == null)
UnregisterLayoutTracking(__targetControl);
else
{
RegisterLayoutTracking(value);

// fix for flicker
__targetControlRect =
value.RectangleToScreen(value.Bounds);

}
}