Mike Morearty
22 May 2006

Undocumented Flex Builder: changing the syntax coloring

Naturally, Flex Builder does syntax coloring when displaying your .mxml, .as, and .css files. As of this first release, we don’t have a way for you to change the colors that are used. But if you don’t like them, you can change them – just please be aware that this technique is entirely undocumented and unsupported. (Doesn’t that just give you a thrill? Funny how learning about anything which is undocumented – even something as trivial as this – makes you feel like you’re stickin' it to the man.)

Anyway, inside your Flex Builder directory, look for a folder called


where XXX is a version number – for example, 340 for Beta 3.

Inside that directory is a file called common.jar. Open this file with WinZip or any other zip software. (In case you didn’t know, Java .jar files are actually the sample file format as .zip files. Probably the easiest way to open the file is to copy common.jar to common.zip, and then just double-click it.)

In there, you will see Colors.xml. That’s your baby. Oh, the excitement, we’ve found the top secret undocumented stuff! The format of the file is pretty obvious: an XML file with three sections – one for ActionScript, one for MXML, and one for CSS. Just modify the following attributes of any tag:

Then when you’re done, save your modified Colors.xml back into common.jar (after first making a backup of common.jar, of course.)

In case it wasn’t obvious: This whole thing is undocumented and unsupported. You do this AT YOUR OWN RISK. And, of course, it may change in future versions of Flex Builder. In fact, it probably will change, when we eventually add support for customizing your colors.

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