Tuesday, December 2, 2008

Making the AJAX Control Toolkit 508 Compliant - TabContainer

The new ASP.NET AJAX Control Toolkit has many useful new controls, but being constrained by Section 508 can make life difficult for those of us wanting to make use of asynchronous browser techniques. Enter the TabContainer control. The TabContainer couldn’t be easier to use. Right out of the box you get a beautiful tab layout using familiar markup:

<ajaxToolkit:TabContainer runat="server" ID="Tabs" Height="138px">

<ajaxToolkit:TabPanel runat="server" ID="Panel3" HeaderText="Email">



<asp:TextBox ID="emailText" runat="server" /><br /><br />

<asp:Button ID="Button1" runat="server" Text="Save" OnClick="SaveProfile" /><br /><br />

Hit Save to cause a full postback.



This results in a nice looking tabbed control:

Now the bad news: if you turn off JavaScript to test 508 accessibility, nothing is displayed because the tabs are rendered as a DIV with style set to visibility:hidden;

<div id="ctl00_ContentPlaceHolder1_Tabs" class="ajax__tab_xp" style="width:402px;visibility:hidden;">

I couldn’t find an easy way to get at the DIV output other than to “overwrite” the style with an Attribute added on PreRender:

Private Sub Tabs_PreRender(ByVal sender As Object, ByVal e As System.EventArgs) Handles Tabs.PreRender

Tabs.Attributes.Add("style", "visibility:visible")

Tabs.ActiveTab.Attributes.Add("style", "visibility:visible")

End Sub

Now that will get your DIV contents visible again, but the tabs no longer work (more JavaScript), so I changed the TabContainer to use a HeaderTemplate and added NoScript tags with buttons:


Signature and Bio


<asp:Button ID="btnTab0" runat="server" CommandArgument="0"

Text="Signature and Bio Tab" OnCommand="Tab_Command" /></noscript>

Add a simple OnCommand handler and you are all set. Note, I prefer to set the handler in this way (declaratively) since I tend to copy/paste my html code and I might always forget to hook up the handler in the CodeBehind:

Protected Sub Tab_Command(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.CommandEventArgs)

Tabs.ActiveTabIndex = Integer.Parse(e.CommandArgument)

End Sub

Without any CSS or HTML trickery this is what you wind up with:

It’s not the most beautiful looking page, but then again, screen readers are by definition not concerned with “look and feel”.

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