Is the ability to change disabled combo-box BackColor a bug or a feature?

Question

I have found the following solution: If I put in the designer:

this.comboBox1.BackColor = System.Drawing.Color.White;  //or any other color
this.comboBox1.DropDownStyle = System.Windows.Forms.ComboBoxStyle.DropDownList; //it has to be that style

I'm able to change the color of comboBox1 - it won't always be grey.

It should be DropDownList and also BackColor should be placed in the designer.

Is it a bug or a feature?

Answer 1

Make custom combobox, and then in WndProc set BackColor for disabled control.

public class ComboBoxCustom : ComboBox {
    [DllImport("gdi32.dll")]
    internal static extern IntPtr CreateSolidBrush(int color);

    [DllImport("gdi32.dll")]
    internal static extern int SetBkColor(IntPtr hdc, int color);

    protected override void WndProc(ref Message m){
        base.WndProc(ref m);
        IntPtr brush;
        switch (m.Msg){

            case (int)312:
                SetBkColor(m.WParam, ColorTranslator.ToWin32(this.BackColor));
                brush = CreateSolidBrush(ColorTranslator.ToWin32(this.BackColor));
                m.Result = brush;
                break;
            default:
                break;
        }
    }
}

Answer 2

The DropDownList is allowed the change of BackColor, and no need to set the colour in the Designer, just set the comboBox property to DropDownList in the properties pane.