The style 'dropShadowVisible' is only supported by type 'mx.controls.List' with the themes(s) 'spark

Question

I'm still plagued by these warnings in my Flex project:-
The style 'dropShadowVisible' is only supported by type 'mx.controls.List' with the themes(s) 'spark'
Clicking on the warnings doesn't take me to the code.
The project started as SDK3.5.  I've made it into an SDK4.0 project.  It uses old Halo components throughout.  I've chosen a Halo theme.
I can get rid of these warnings if I "Use Flex 3 compatibility mode".  BUT, If I use that mode, I get also Run Time Errors - so I decided against this compatibility, and just edited the styling, deprecated syntax, and a few issues to make the app work.
I tried the solution someone suggested editing the flex-config.xml file, but it didn't work for me.
The application begins...
<mx:Application
xmlns:fx="http://ns.adobe.com/mxml/2009"
xmlns:mx="library://ns.adobe.com/flex/mx"
xmlns:s="library://ns.adobe.com/flex/spark"
(I've obviously tried clean).

Answer 1

Yes, very irritating. "Only a warning" isn't the whole story, it's more than just an annoyance, it can potentially make all warnings useless.
Imagine cases where you have multiple warnings (often FB warnings turn up for EACH component resulting in many repeats, design mode is particularly bad with this).  Having a ton of warnings that "aren't really warnings" obscures REAL warnings that we'd want to do something about (and makes errors harder to notice at first--you're so used to always seeing lines under the problems tab that you don't always notice a new error that just popped up).  In the worst case scenario a valid warning that would have prevented a bug is missed and something goes to QA or production that should have been caught at compile time...
This wouldn't be nearly as annoying if we had some decent way of filtering these warnings from the problems tab. The current filter isn't good enough and only seems to allow you to filter out one message due to the way it works, but sometimes we see more than one type of "bogus" warning.
Voted and added to comments.  I wonder if there's a feature request out there to improve warning filter capabilities?  I also wonder why nobody complained about this before, it seems pretty easily visible.  Is it the norm for people to just always ignore warnings?  This isn't a good practice, warnings tend to exist for a reason.
(Btw, this is part of my reasoning for the claim that Halo seems to have become a "second class citizen" component set - hopefully Adobe can do something about this.)