Spark-only ProgressBar?

In the Flex4.5 docs it says

The ProgressBar 开发者_如何学Gocontrol is part of the MX component set. There is no Spark equivalent.

This is a problem for apps that are Flex4-only (such as a mobile app). What are people doing to work around this?

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This might get you started with a progress bar: http://aaronhardy.com/flex/spark-progressbar/

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This isn't true for mobile flex projects. Mobile projects require that you use components from the Spark namespace. What have people been doing for progress bars on mobile? I currently have one I made by stretching a single colored image across the bottom of the screen, it works but doesn't have the 3d look, feel, and animation of a real progress bar.