Override the drawing of some .Net Framework controls to change its border color?

Question

SCENARIO

I\'m using a 3rd party windows visual theme.

When I see my application, it looks like this:

Answer 1

You can catch the WM_PAINT or WM_ERASEBKGND message and draw the border manually:

[DllImport("user32.dll")]
static extern IntPtr GetWindowDC(IntPtr hWnd);

[DllImport("user32.dll")]
static extern int ReleaseDC(IntPtr hwnd, IntPtr hDC);

protected override void WndProc(ref Message m)
{
    IntPtr hdc;
    if (m.Msg == 0x14) //WM_ERASEBKGND
    {
        hdc = GetWindowDC(m.HWnd);

        if (hdc != IntPtr.Zero)
        {
            using (Graphics g = Graphics.FromHdc(hdc))
            {
                g.DrawRectangle(Pens.Red, 0, 0, this.Width-1, this.Height-1);
            }
            ReleaseDC(m.HWnd, hdc);
        }

    base.WndProc(ref m);
}

It does have however a problem when the textbox looses it's focus.