Creating an overlaying transparent control

[felix]

Hi,

I'm trying to subclass System.Windows.Forms.Control to create a Control
that is fully transparent. I'd like to place this control over other
Controls in order to display additional information.

Unfortunately, as soon as the Control is placed on to with BringToTop(),
all underlying Controls aren't painted anymore.

The constructor looks like this:
....
public OverlayPaintControl()
{
// Enable doubleBuffering
this.SetStyle(ControlStyles.DoubleBuffer |
ControlStyles.UserPaint |
ControlStyles.AllPaintingInWmPaint,
true);
this.UpdateStyles();

SetStyle(ControlStyles.SupportsTransparentBackColo r, true);
SetStyle(ControlStyles.Selectable, false);

this.BackColor = Color.FromArgb(0, 0, 0, 0);
}
....

And I used it as in the following:
....
_overlayControl.Location = new Point(0, 0);
_overlayControl.Size = this.Size;
_overlayControl.Enabled = false;
_overlayControl.Anchor = AnchorStyles.Bottom | AnchorStyles.Left |
AnchorStyles.Right | AnchorStyles.Top;
Controls.Add(_overlayControl);
_overlayControl.BringToFront();
....
Does anyone has an idea how to handle this??

Thanks and best regards,
Felix