Is it Sencha's position (as implied here:
http://www.sencha.com/forum/showthre...stroying-twice)

that bugs will only be fixed in v3 for support tickets? When an acknowledged bug is reported, and especially when it's already been fixed in v4 so the fix is known, to fail to fix it in v3 is basically stating that v3 is unsupported.

We need a clear statement as to what the continued support for v3 entails as v4's performance continues to preclude using it.