I'm sure this isn't specific to the AjaxControlToolKit, but it is what is causing me issues. I've created a basic user control that essentially wraps a textbox and MaskedEditExtender because it will often be used on different pages. The designer of the control looks fine, but when I include it in a page, I see a box for the MaskedEditExtender, which gets a bit annoying when designing. It looks like this in the designer:
Is there a way to hide this box in the designer, so my control just shows up as a text box?