Help Adding Design Time Functionality To A Custom WebControl

Experts,

I recently began making a few custom WebControls and wanted to get some advice on how to enhance the design time functionality in Visual Studio. Specifically I would like to know how to create a list of pre-defined options for a property. Much like "server" appears when you type runat="

Also, I would like to know exactly how to work with an enum value at design time. A great example of this is the TextBoxMode enum for the TextBox asp.net control. When you declare the control in an .aspx page, you pass a string value TextMode="singleline". However, the value is actually an enum:

TextBox tb = new TextBox();
tb.TextMode = TextBoxMode.SingleLine;

I have done a little digging, but most of what I find is the basic "this is how to add a title and description to your class" tutorials. Hopefully I can find one of you custom control experts that can point me in the right direction. Thanks much for your time so far!

~ C