I am trying to animate (slide down) the list that pops up when in the "open"
state of the ComboBox or DropDownList in Spark.
I am defining a custom Skin for that and I guess should deal with the popUp of
the PopUpAnchor. Since the PopUpAnchor is "attached" to the root, when animating
it is fully visible and stays on top of all the content I have on the page.
There is a "useful" comment for me in the default skin, but whatever I tried it
The PopUpAnchor control that opens the drop-down list.
<p>In a custom skin class that uses transitions, set the
<code>itemDestructionPolicy</code> property to <code>none</code>.</p>
Is there any workaround for slide down animation of the popup list ? Tried
masking it, no luck...
Spending hours on docs, research and experiments I came up with three possible solutions (neither is ideal):
#1 Go back to MX ComboBox component, which has a slide down effect by default
#2 Try emulating (right, do not slide down, try to "fake" user with combination of several effects that will make it look like a slide down) the slide down behavior in Spark ComboBox/DropDownList.
I went with this solution and used the sequence of effects.
For "normal" to "open" state: Sequence (fade out your content immediately, but leave background visible; ScaleY background from 0 to 1, fade in your content).
#3 Write your own component
I filed a feature request in Jira, please vote for it: Slide down possibly is the most meaningful behavior for these components and currently this behavior is not supported.