We have currently several enhanced versions of .NET controls (textbox,
combobox checkbox label etc) so that they automtically comform to our
applications look and feel. Everything seems to work fine except for out
enhanced textbox.  Our textbox (like our other enhanced controls)
automatically sets the control's background colour based on it being
readonly/mandatory/enabled etc and this all seems to work apart from in
readonly mode.  In the readonly mode .NET does not call our implementation of
the BackgroudColor property and instead of usnig the colour we have defined
(yellow for readonly textboxes) it uses the default grey colour for readonly.
I have included a cutdown version of our implementation below and any help
would be appreciated.

public class EnhancedTextBox : TextBox
    {
        #region " Auto-generated code. "

        /// <summary>
        /// Required designer variable.
        /// </summary>
        private System.ComponentModel.Container components = null;

        public EnhancedTextBox()
        {
            // This call is required by the Windows.Forms Form Designer.
            InitializeComponent();
        }

        /// <summary>
        /// Clean up any resources being used.
        /// </summary>
        protected override void Dispose( bool disposing )
        {
            if( disposing )
            {
                if(components != null)
                {
                    components.Dispose();
                }
            }
            base.Dispose( disposing );
        }

        #region Component Designer generated code
        /// <summary>
        /// Required method for Designer support - do not modify
        /// the contents of this method with the code editor.
        /// </summary>
        private void InitializeComponent()
        {
            components = new System.ComponentModel.Container();
        }
        #endregion

        #endregion

        private bool mblnMandatory = false;

        /// <summary>
        /// blnMandatory gets/sets the mandatory flag for the field, forcing the
control to be redrawn when the field is set.
        /// </summary>
       
        [Description("Indicates if the field is mandatory or not and is also used
to dictate the field's background colour."), DefaultValue(false)]
        public bool Mandatory
        {
            get
            {
                return(mblnMandatory);
            }
            set
            {
                mblnMandatory = value;
                // Refresh the control so the background colour is set correctly.
                this.Refresh();
            }
        }
        /// <summary>
        /// ReadOnly gets/sets the mandatory read only flag for the field.
        /// </summary>
        /// <remarks>ReadOnly overrides the base class ReadOnly property and when
being set, it forces the control to be redrawn to update it's
        /// background colour.</remarks>
       
        [Description("Indicates if the field is read-only or not and is also used
to dictate the field's background colour."), DefaultValue(false)]
        public new bool ReadOnly
        {
            get
            {
                return(base.ReadOnly);
            }
            set
            {
                base.ReadOnly = value;
                // Refresh the control so the background colour is set correctly.
                this.Refresh();
            }
        }

        /// <summary>
        /// BackColor gets/sets the background colour to be used for the control.
        /// </summary>
        /// <remarks>BackColor overrides the base class BackColor property and
returns the background colour based on the control's
        /// enabled/mandatory/readonly status.</remarks>
       
        [Description("Indicates the background colour for the control.")]
        public override Color BackColor
        {
            get
            {
                // If the control is enabled then use the correct background colour.
                if(Enabled)
                {
                    if(!base.ReadOnly && !mblnMandatory)
                    {
                        return(SystemColours.gcolEditableTextBackground);
                    }
                    else if(base.ReadOnly)
                    {
                        return(SystemColours.gcolReadOnlyBackground);
                    }
                    else
                    {
                        return(SystemColours.gcolTextMandatoryBackground);
                    }
                }
                    // Else the control is not enabled so return the current background
colour.
                else
                    return(base.BackColor);
            }
            set
            {
                base.BackColor = value;
            }
        }

    }