With Flex 4 is should work, as RTL languages are suppoprted, whereas they are not adequately supported in Flex 3.
Check the version of Flash Player being used to render your app. Go to Adobe Labs to get the latest version.
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Thanks Greg Lafrance for your response.
Still my problem is not sloved 100%,some thing is still missing.http://forums.adobe.com/people/Greg%20Lafrance
I am attaching an image file with this. If you will look at the image, the Arabic words are not complete while displaying.
Awaiting for your prompt response.