When authoring a custom ASP.NET control, I believe it a best practice to store public properties in the control’s viewstate. This applies to both controls inheriting from WebControl and to user controls.

[System.ComponentModel.DefaultValue("MyDefault")]
public string MyProperty
{
get { return ViewState["MyProperty"] as string ?? “MyDefault”; }
set { if (MyProperty != value) ViewState["MyProperty"] = value; }
}

The only thing to remember when using the snippet is if ou use a value type (int, Decimal, etc) you need to change the inner cast to use Nullable, which is really easy in C#. Just type a “?” mark as the snippet places the cursor right where you need it when you finish.

[System.ComponentModel.DefaultValue(42)]
public int TheMeaningOfLife
{
get { return ViewState["TheMeaningOfLife"] as int? ?? 42; }
set { if (TheMeaningOfLife != value) ViewState["TheMeaningOfLife"] = value; }
}