Closed Issue: BUG: MaskedEditValidator CSS/Visibility Error [13041]

In the 20Sep07 release, if the target of a MaskedEditExtender becomes invisble (in my case, a container asp:Panel has its Visible property set to False on a partial postback), subsequent partial postbacks result in a javascript error because the MaskedEditValidator tries to manipulate the css classes of the textbox. As the textbox is no longer visible, and henceforth not rendered to the page, $get returns null, and an Object Expected javascript error is given because the target is null.

Stack Trace: (The first number is when I debug the error in VS2005. The second number is from the Source Project)
Line 6151: if (e) throw e;
<<in Sys.UI.DomElement.removeCssClass in MicrosoftAjax.js>>
Line 22 (50): Sys.UI.DomElement.removeCssClass(target,value.InvalidValueCssClass);
<<in MaskedEditSetCssClass in MaskedEditValidator.js>>
Line 335 (653): MaskedEditSetCssClass(value,"");
<<in MaskedEditValidatorNone in MaskedEditValidator.js>>
Line 208: val.isvalid = val.evaluationfunction(val);
<<in ValidatorValidate>>
Line 128: ValidatorValidate(Page_Validators[i],validationgroup,null)
<<in Page_ClientValidate>>

Note that this broken functionality was not present in the previous official release.
Comments: This ticket was filed for a pre-15.1 version of AJAX Control Toolkit. If this is still an issue in v15.1 or later, please create a new inquiry.