C# Winform Button, make the border thicker and different color?

It is possible if you subclass the control and handle the paint event manually. Here is the crudest of examples to get you started.

    public class MyButton : Button
    {
        private bool _isClicked = false;

        protected override void OnPaint(PaintEventArgs pevent)
        {
            base.OnPaint(pevent);
            if (_isClicked)
            {
                pevent.Graphics.FillRectangle(Brushes.Red, this.ClientRectangle);
            }
        }

        protected override void OnClick(EventArgs e)
        {
            base.OnClick(e);
            this._isClicked = true;
        }
    }

Select allOpen in new window

You would still need to draw the border and text to make it look right.

How do I do it only when it is clicked?

That's what overriding the OnClick method is for and the private member _isClicked.

that did it!

thanks!