I am trying to draw a TextBox on the extended glass frame of my form. I won't describe this technique, it's well-known. Here's an example for those who haven't heard of it: http://www.danielmoth.com/Blog/Vista-Glass-In-C.aspx

The thing is, it is complex to draw over this glass frame. Since black is considered to be the 0-alpha color, anything black disappears.

There are apparently ways of countering this problem: drawing complex GDI+ shapes are not affected by this alpha-ness. For example, this code can be used to draw a Label on glass (note: GraphicsPath is used instead of DrawString in order to get around the horrible ClearType problem):

public class GlassLabel : Control
{
    public GlassLabel()
    {
        this.BackColor = Color.Black;
    }

    protected override void OnPaint(PaintEventArgs e)
    {
        GraphicsPath font = new GraphicsPath();

        font.AddString(
            this.Text,
            this.Font.FontFamily,
            (int)this.Font.Style,
            this.Font.Size,
            Point.Empty,
            StringFormat.GenericDefault);

        e.Graphics.SmoothingMode = SmoothingMode.HighQuality;
        e.Graphics.FillPath(new SolidBrush(this.ForeColor), font);
    }
}

Similarly, such an approach can be used to create a container on the glass area. Note the use of the polygons instead of the rectangle - when using the rectangle, its black parts are considered as alpha.

public class GlassPanel : Panel
{
    public GlassPanel()
    {
        this.BackColor = Color.Black;
    }

    protected override void OnPaint(PaintEventArgs e)
    {
        Point[] area = new Point[]
            {
                new Point(0, 1),
                new Point(1, 0),
                new Point(this.Width - 2, 0),
                new Point(this.Width - 1, 1),
                new Point(this.Width -1, this.Height - 2),
                new Point(this.Width -2, this.Height-1),
                new Point(1, this.Height -1),
                new Point(0, this.Height - 2)
            };

        Point[] inArea = new Point[]
            {
                new Point(1, 1),
                new Point(this.Width - 1, 1),
                new Point(this.Width - 1, this.Height - 1),
                new Point(this.Width - 1, this.Height - 1),
                new Point(1, this.Height - 1)
            };

        e.Graphics.FillPolygon(new SolidBrush(Color.FromArgb(240, 240, 240)), inArea);
        e.Graphics.DrawPolygon(new Pen(Color.FromArgb(55, 0, 0, 0)), area);

        base.OnPaint(e);
    }
}

Now my problem is: How can I draw a TextBox? After lots of Googling, I came up with the following solutions:

• Subclassing the TextBox's OnPaint method. This is possible, although I could not get it to work properly. It should involve painting some magic things I don't know how to do yet.
• Making my own custom TextBox, perhaps on a TextBoxBase. If anyone has good, valid and working examples, and thinks this could be a good overall solution, please tell me.
• Using BufferedPaintSetAlpha. (http://msdn.microsoft.com/en-us/library/ms649805.aspx). The downsides of this method may be that the corners of the textbox might look odd, but I can live with that. If anyone knows how to implement that method properly from a Graphics object, please tell me. I personally don't, but this seems the best solution so far. To be honest, I found a great C++ article, but I am way too lazy to convert it. http://weblogs.asp.net/kennykerr/archive/2007/01/23/controls-and-the-desktop-window-manager.aspx

Note: If I ever succeed with the BufferedPaint methods, I swear to s/o that I will make a simple DLL with all the common Windows Forms controls drawable on glass.