A Tale of Tabbed Pages

The Design: In my ASP.NET content manage­ment system, I wanted to use a tab control to allow an author to edit individual pages of an article. I also decided to use Active­Up's HtmlTextBox control to enable rich-text editing: it's a full-featured control at a very reasonable price.

The Problem: I quickly discovered, however, that changes to the text box weren't being saved when I switched to a different tab. After another marathon session of cursing and semi-random code-tweaking (I tried changing viewstate settings, attaching code to various page and control events, etc.), I finally concluded that the postback triggered by a change of tabs was circumventing the text box's onblur event, which is where it persists its contents. (I should mention that in my desperation, I took advantage of ActiveUp's live chat tech support feature. Pierre, the control's author, was extremely cordial and helpful. Since he's in Belgium and I tend to work in the middle of the night, the arrangement proved to be convenient for both of us!)

The Solution: Now that I understood the source of the problem, the question was: How do I force the text box to persist its data before a postback? I tried a few things, and eventually found a solution by Googling for "intercept __doPostBack": The trick was to create my own function that does whatever I need to do before a postback, and then create a function pointer that redirects the default __doPostBack function to my custom function (JavaScript is awesome, by the way). Problem solved!

Footnote: Another problem I had with the HtmlTextBox was that I couldn't get a second control on the page to work correctly. Pierre assured me that this is supported, so I took a closer look at my code. Turns out that the ID I was assigning to the second control contained a space (I create the controls dynamically based on an XML form definition -- that's a subject for another article -- and I was assigning an ID equal to the name of the data field). Replacing the space with an underscore solved that problem.