Click through transparency for Visual C# Window Forms?

I made a panel and set it to fill the screen, now I can see the windows under it but I want it to be click through, meaning they could click a file or see a tool tip of another object through the transparency.

RE: This may be too obvious, but have you tried sending the panel to the back by right clicking and choosing "Send to Back"?

I mean like the desktop or firefox, not something within my project.

Creating a top level form that is transparent is very easy. Just make it fill the screen, or required area, and define it to have a TransparenyKey color and BackColor of the same value.

Getting it to ignore the mouse is simple enough, you just need to override the WndProc and tell the WM_HITTEST that all mouse positions are to be treated as transparent. Thus causing the mouse to interact with whatever happens to be underneath the window. Something like this...

    protected override void WndProc(ref Message m)
    {
        if (m.Msg == (int)WM_NCHITTEST)
            m.Result = (IntPtr)HTTRANSPARENT;
        else
            base.WndProc(ref m);
    }