Stillnet Studios

Sometimes its helpful to allow users to dynamically add or remove elements from a form. An example might be an image upload page, where you want to allow users to upload a varying number of images. Using JavaScript you can easily place more/less links on the page that show and hide form elements.

This is often done by placing a large number of elements on the form, and setting most of them to be initially hidden with CSS. When the user clicks the “show” link, the next element is unhidden. This is not the best solution however, especially when there is a possibility of having tens of elements - thats a lot of unnecessary html to send down the pipe and render.

Another method is to actually create and destroy elements using the DOM functions. Here’s how I did this recently on a page that need to have any number of form elements.
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When debugging a Flex 3 application on Vista / IE 7, you may encounter this error when debugging an application for the second time.

Another flash debugger may be running. Close it to Continue.

Even though it appears there are no IE instances still running, this error comes up.

There are several solutions to this, one is to configure Flex Builder to launch a different browser for debugging, such as FireFox. Another is to disable Vista’s UAC. Neither of these were good solutions for me.

The problem has to do with a socket getting left open. As a short term fix you can use your task manager and kill the ieuser.exe process when you get this error. Then you should be able to launch the debugger ok.

This bug is discussed in Adobe’s bug tracker system. Their suggested solution for now is to add this string to your flexbuilder.ini file:

-Djava.net.preferIPv4Stack=true

After searching around for a while and not finding my flexbuilder.ini file, I discovered that file only exists if you’ve installed Flex Builder stand alone. If you install it as an eclipse plug-in, as I have, then you need to add that line to eclipse.ini. But that didn’t solve the problem for me, and I’ve read it didn’t solve it for some other people as well.

My solution was to add it to the shortcut I was using to launch Flex Builder. This solved the problem and I can now debug as many times as I want with no errors.