C# Remove flickering in MDI applications.

If you have ever been working with MDI applications, and while to MDI windows are while the MDI windows are maximized and you switch you see a flicker of the windows.

Well below is a simple quick fix for solving this issue.

So firstly lets define some constants that we will be using.

const int WM_NCPAINT = 0x85;
const int WM_SIZE = 0x05;

Now override the WndProc method in the MDI child window(s).

protected override void WndProc(ref Message m)
{
    if (m.Msg == WM_NCPAINT) 
    {
        if(this.WindowState == FormWindowState.Maximized)
            return;
    }

    if (m.Msg == WM_SIZE)
    {
        if (this.WindowState == FormWindowState.Maximized)
            return;
    }

     base.WndProc(ref m);
}

and viola your flickering issues are gone.