The ASDocs are just HTML and there is not an explicit component like that in Flex. I assume the 'window' on the ASDocs is some form of AJAX but haven't reviewed code.
But, it should be easy to create one.
<mx:VBox>
<mx:TextInput id="input" visible="true" />
<mx:Button id="expandCollapseButton" visible="true" label=">" click="onClick()" />
</mx:VBox>
In your onClick method do something like this:
public function onClick():void{
if(this.expandCollapseButton.label == '>'){
this.input.visible=false;
this.input.includeInLayout=false;
this.expandCollapseButton.label = "<";
} else {
this.input.visible=true;
this.input.includeInLayout=true;
this.expandCollapseButton.label = ">";
}
}
States, as mentioned in a comment to your question may be another way to implement this. I'm sure there are others.
I would think hard about what you're trying to accomplish. I find the yellow box non-intuitive and very annoying. I hav to click a "play" button to hide it. "Play" usually means goto and for the longest time I would not click it because I didn't want to leave the page.
Disclaimer: Code written in browser