ToolTip window help in Flex

How i can create pop-up window (with some text)when focus on TextInput (like in w开发者_开发问答indows xp when i focus mouse cursor on file it shows short info).

ps: example of pop-up in windows xp alt text http://img38.imageshack.us/img38/3884/2222ty.gif

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The form of window you are referring to is generally refered to as a "Tooltip"

I think that this is what you're looking for.