asp.net control to expand textbox?

I'm not sure what this functionality is properly called. But I have a single-line t开发者_StackOverflow社区ext box in an asp.net gridview. When a user clicks on that textbox, I want a larger, multi-line textbox to pop-up, so they can see the entire contents and edit it. This expanded view would go away once the focus moves to another control.

Is there a control out there that allows for this? If not, how could I go about implementing one?

EDIT: I'm looking for similar function to how the TextBoxCalendar Extender works, but instead of a calendar, I'd like a multiline textbox to pop.

This blog post has an elastic textbox that uses jQuery. According to the author,

...when the TextBox gets the focus, it will expand to a specified height and width and then when it loses focus it will contract back to it’s more compact size.

You will need to look at using javascript/jquery if you want to do this without a postback (which I would recommend).

The link below goes over a good method for doing this:

• http://www.webdeveloper.com/forum/showthread.php?t=175514

Here is the function they call:

   function expand(width,height)
    {

    document.getElementById("text_output").cols = width;
    document.getElementById("text_output").rows = height;

    }

There may also be a control in the .net AJAX tool kit that does this, but the javascript route would probably be simpler.

UPDATE:

If you are looking for popup functionality then I would definately go the jQuery route. Typically they will have you specify a div that you would like to have popup on a certain event. The link below gives you a number of modal popup plugins that you can look at using:

• http://choosedaily.com/1178/15-jquery-popup-modal-dialog-plugins-tutorials/

If your talking about an asp.net Textbox you can specify the number of rows like so:

    <asp:TextBox id="tb6" rows="5" TextMode="multiline" runat="server" />

See this link for more info

You can just use a textbox control, and add an onclick Event handler that changes the "rows" property to something greater than 1, thus multi-line.