I've been having a small but rather annoying (for me) problem since the patch and new version of xperl has come out. I tried to use that bugsack program but it said everything was ok, so I'll do my best to describe it.
Basically, I use this macro to cast:
#showtooltip Shadow Bolt
/console Sound_EnableSFX 0
/console Sound_EnableSFX 1
/cast Shadow Bolt
Generally when i am attacking, i will click to start casting the next spell before the current one has finished its cast. It has never been a problem before, the macro stops any error messages when the trinket is on cooldown, and i've always been able to do the chain casting without a problem.
But I have noticed now with the new version of xperl that when i hit the button again to cast, the cast bar on my portrait will come up with 'failed' and a red background. From what i can tell it either doesnt interrupt the actual spell being recast, or if it does its minor. Generally by the time the new castbar appears, it's already in progress so it means I cannot time my next recast properly.
The old WoW cast bar flows just as it always does when i re-enable it, it's just the castbar with xperl that goes funny.
Ok that probably makes no sense so my apologies. I took a screenshot to try to give you an idea of what I mean. You can see with the WoW castbar it is still in progress, at this point I had already re-pressed my spell/macro button. The WoW bar flows fine, but the castbar on my portrait does exactly what is pictured, stops the progress and pops up with that, and it stays there until the cast time is up and the new spell is being cast.
Once again I really hope I havent waffled on too much with my explanation. I'm pretty terrible when it comes to that, and it being late here doesnt help either!