Kudos for pointing this out.
-Dan

http://myflex.wordpress.com/2009/12/20/adding-width-height-x-and-y-into-the-css-model-of-flex/

In flex, there is no clean way to suck in a css that works perfectly when used at compile time but instead feed it at runtime to produce the same effect… Yes, I’ve seen CSSParsers and all but none of them really work to the full extent required.

Yes you can use a urlloader, load the stylesheet and use the following pseudo code

var sheet = new StyleSheet();
sheet.parseCSS(cssdatareadfromurl);

var styleCount:int = sheet.stylenames.length;

for each style read into array
currSelector = new CSSStyleDeclaration();
set all styles using this selector
i.e currSelector.setStyle(prop, value);

StyleManager.setStyleDeclaration(stylename, currSelector, true);

But you will notice that most of your styles do not work for many reasons.

1. The stylesheet parser lowercases all style selector names – so you cannot really use any of this stuff…

2. If you figure out a way to preserve the names, then things like gradients etc that require comma separated values would cause a runtime exception.

3. To overcome problem 2, convert all comma separated values into arrays using the String.split() method. You will not see runtime exceptions anymore…

4. But gradients don’t work, background images don’t work, and many of the styles that work when used at compile time just do not work when fed into the style manager at runtime…

From my experience runtime styling or style overriding is a big can of worms (buggy code/design) using the Stylemanager.setStyle functionality…

If you are doing dainty things like changing the background color then there are no problems!

I just started working with Flex so I may be wrong..

Too true, unfortunately. Currently causing me a big headache.

Update – We have 16 votes for this feature request so far. That brings the feature up to #4 in the Flex bug-base.

http://www.onflexwithcf.org/index.cfm/2007/10/19/Flex-Roadmap-presented-by-Ely-Greenfield–Videos