Custom GroupBox with custom TextColor, BorderColor and Transparent BackColor
<p>I'm using <code>WinForms</code>. In my form I have a <code>GroupBox</code>. This is a <strong><em>custom</em></strong> group box. I wanted a transparent background for the <code>groupbox</code>. I'm having issues creating a transparent background for the <code>groupbox</code> The problem with this code is i keep on getting an error when i set the group box <code>backcolor</code> to transparent. </p>

<blockquote>
  <p>Error: Control does not support transparent background colors. </p>
</blockquote>

<p><code>g.Clear(BackColor = Color.Transparent);</code> (This is the line that is giving me the problem)</p>

<pre><code>    private void DrawGroupBox(GroupBox box, Graphics g, Color textColor, Color borderColor)
    {
        if (box != null)
        {
            Brush textBrush = new SolidBrush(textColor);
            Brush borderBrush = new SolidBrush(borderColor);
            Pen borderPen = new Pen(borderBrush);
            SizeF strSize = g.MeasureString(box.Text, box.Font);
            Rectangle rect = new Rectangle(box.ClientRectangle.X,
                                           box.ClientRectangle.Y + (int)(strSize.Height / 2),
                                           box.ClientRectangle.Width - 1,
                                           box.ClientRectangle.Height - (int)(strSize.Height / 2) - 1);

            // Clear text and border
            g.Clear(BackColor = Color.Transparent);

            // Draw text
            g.DrawString(box.Text, box.Font, textBrush, box.Padding.Left, 0);

            // Drawing Border
            //Left
            g.DrawLine(borderPen, rect.Location, new Point(rect.X, rect.Y + rect.Height));
            //Right
            g.DrawLine(borderPen, new Point(rect.X + rect.Width, rect.Y), new Point(rect.X + rect.Width, rect.Y + rect.Height));
            //Bottom
            g.DrawLine(borderPen, new Point(rect.X, rect.Y + rect.Height), new Point(rect.X + rect.Width, rect.Y + rect.Height));
            //Top1
            g.DrawLine(borderPen, new Point(rect.X, rect.Y), new Point(rect.X + box.Padding.Left, rect.Y));
            //Top2
            g.DrawLine(borderPen, new Point(rect.X + box.Padding.Left + (int)(strSize.Width), rect.Y), new Point(rect.X + rect.Width, rect.Y));
        }
    }

    private void groupBox1_Paint(object sender, PaintEventArgs e)
    {
        GroupBox box = sender as GroupBox;
        DrawGroupBox(box, e.Graphics, Color.Red, Color.Blue);
    }
</code></pre>

<p><code>g.Clear(groupBox1.BackColor = Color.Transparent);</code></p>

<p>If i do this i get: </p>

<blockquote>
  <p>This example consists of a <code>Panel</code> with a dice image inside the panel,
  and the custom <code>Groupbox</code>.</p>
</blockquote>

<p><a href="https://i.stack.imgur.com/9k5hr.png" rel="noreferrer"><img src="https://i.stack.imgur.com/9k5hr.png" alt="enter image description here"></a></p>