Custom Control Appearance
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I created my own user controls that inherit from the standard .net controls (for example MyTextBox : TextBox).  MyTextBox has within it some custom logic, and also sets some style properties (eg colour).  I build the project that contains these controls, and they get added to my toolbox.  I then drag them onto the windows form designer.  The problem is that when I drag them, the windows form designer automatically includes the style definition for the control that i dragged.  For example
>>this.myTextBox1.BackColor = System.Drawing.Color.Gray;

Now, if later on during development I decide to change the colour for all instance of MyTextBox in the solution from Gray to White, I cannot simply go to the MyTextBox control code, change it there and rebuild.  The change will not be applied to existing text boxes, since this property will be overridden in the forms designer!  What is the best approach to handle such cases?