SWF "loading" icon in a flex combobox drop down

In the flex web app i'm working on, i need to show a loading icon (an SWF spinner) in the combobox drop down until the user list is initiali开发者_如何学编程zed. Is there any way to do this?

You need to extend ComboBox, suppress dropdown appearance if data not ready, and show some replacement of dropdown with animation. When data is ready, set it into dataProvider and open dropdown programmatically.

showBusyCursor = true when the data starts to load.
showBusyCursor = false when you are done getting the data.