How can we simulate the Indesign paragraph rules in Adobe Flex4?

Interesting problem! Here's a suggestion to try.

Make your own ContainerController class that derives from ContainerController and overrides the addTextLine protected method. Each time a line is added, check it to see if it is the first or last line of the paragraph (assuming you wanted rules above and below). If so, then create a new DisplayObject for the rule, and make the rule a child of the TextLine. Then call super.addTextLine, which will add the TextLine to the container. To determine whether the line is first or last, get the TextFlowLine from the TextLine's userData. The TextFlowLine has a location property which will tell you if the line is first, last, middle, or only. To get TLF to use your derived ContainerController class, pass in one of your ContainerController's when you call addController on the textFlow's flowComposer.

So, your code might look something like this:

textFlow.flowComposer.addController(new RuleContainerController(sprite, width, height));

class RuleContainerController extends ContainerController

{

     override protected function addTextLine(textLine:TextLine, index:int):void

     {

          var line:TextFlowLine = textLine.userData as TextFlowLine;

          if (line.location & TextFlowLine.LAST)

          {

               ruleAfter:DisplayObject = // set up the rule here

               textLine.addChild(ruleAfter);

          }

          super.addTextLine(textLine, index);

     }

This code will add a rule to every paragraph, which may not be what you want. But you could add a user property that you add to the paragraph, and then the addTextLine could use the TextFlowLine to get the paragraph and only attach the rule if property is set.

This is really just sketched out, I haven't compiled or debugged it or anything, but it seems like it might work for your problem. Let me know how it works!

- robin