Winforms Disabling Control Box from showing up

I am creating a Winforms application without开发者_开发百科 any Toolbars. The main window has FormBorderStyle set to Sizable and ControlBox is set to true. Every time I hit Alt and then use Up or Down (not Alt+Up or Alt+Down) the control box shows up on the top left hand side of my application. This is annoying because there are shortcuts like Alt+R available in my grid, and if the user just presses and releases Alt and then Up to go to previous row the control box shows up.

How can I override this?

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@Ken: I tried your code and focus was still going to ControlBox for some reason. Tweaked it a bit and it worked perfectly for my needs.

protected override bool ProcessCmdKey(ref Message msg, Keys keyData)
{ 
    if (keyData == (Keys.RButton | Keys.ShiftKey | Keys.Alt))
    { return true; }
    return base.ProcessCmdKey(ref msg, keyData); 
 }

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How about this:

protected override bool ProcessCmdKey(ref Message msg, Keys keyData)
{
    if (keyData == Keys.Alt)
    {
        keyData = Keys.None;
    }
    return base.ProcessCmdKey(ref msg, keyData);
}

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Did you try setting ShowIcon to false?