When making examples for a recent workshop, I stumbled over a bug in the Actionscript Virtual Machine used for Flash Player 9 and higher (AVM2). If you are using a movieclip inside a button, the hit area won’t work as it should. When moving the mouse across the button, it will constantly blink giving a very flimsy impression. You can test this in the example below.
Switching the movieclip to graphic fixes the issue, but why won’t this work? It’s always worked well before, so this must be a bug in AVM2? Another thing is that if you hover this button for a few seconds, the Flash IDE crashes instantly…
If you’re unable to repoduce the bug - feel free to check this video that shows it and please post a comment telling what Flash Player version/browser you are using. I’ve been able to reproduce the bug on all OSX browsers + IE8 on Win7.
Submitted this as a bug in the bugbase https://bugs.adobe.com/jira/browse/FP-439622 April 2010 at 3:38 pm