ImageBox Paint

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C#

Hi,

I have a small problem which I can't fix. I hope someone out there can teach me how. Here is the problem:

I have a hardware a keyboard and writing a test application for it. To test if the buttons are pressed. When a button pressed I am drawing a rectangle on it. but the problem is when i release the button rectangle disappears. I want to stay there with all the pressed buttons. like when i hit button 1 and button 2 I want them both display rectangles and keep them on the form.

Here is my code:

private void ImageBox_Paint_1(object sender, PaintEventArgs e)
        {
            if (buttcorrs != null && buttcorrs.Count() == 4)   
            {
                e.Graphics.FillRectangle(Brushes.Green, buttcorrs[0], buttcorrs[1], buttcorrs[3] - buttcorrs[1], buttcorrs[2] - buttcorrs[0]);
                ImageBox.Invalidate(); 
                //Array.Clear(buttcorrs, 0, buttcorrs.Length);
            }

buttcorrs is an array where i send the coordinates as a unicode from the device. as I said when i hit another key it deletes the rectangle and displays a new one on the new button.