If you need to expand InputFormTextBox control and CssClass property seems to be not working, continue reading this post.

I’ve created an application page and I used an InputFormTextBox control to give users the possibility to write some html content. This is the code I used:

<wssawc:InputFormTextBox 
          Title="My Field" 
          ID="myField" 
          Rows="15" 
          Runat="server" 
          TextMode="MultiLine" 
          RichText="true" 
          RichTextMode="FullHtml"/>

You can see the page rendering in the following picture:

As you can see, the control’s width is not at 100% of available space.

Trying to enlarge the control with style and CssClass attributes were unsuccessful. I made some investigations and I discovered that code rendered by the control simply ignores those attributes.

Looking at html generated by the control, I saw that it is rendered as two main element, a table element to display the toolbar and an iframe element for the html container. Both have a css class defined, ms-rtetoolbarmenu for the table (toolbar) and  ms-rtelong for the iframe (html container).

My solution to the problem was to override those classes with the following code

<style type="text/css"> 

table.ms-rtetoolbarmenu{ 
    width:100%;
} 

iframe.ms-rtelong{ 
    width:100%;
} 

</style> 

The page rendering after this modify was:

Hope this can help you.