Worker.createFilter: Component returned failure code: 0x80004005
(NS_ERROR_FAILURE) [nsIMsgFilter.getActionAt]

Thanks for raising the bug. I will post the try out version that I already sent
you here for others to test. The error that is thrown happens internally in
Thunderbird code (and would be triggered by one of your filters).
getActionAt(n) is called in more than one place in code, so I might not have
put the fix in the right place (I put it in the merge action). Can you give
more context, what exactly did you do to create the error?

Created an attachment (id=7554) [details]
1.8 prerelease 4

Here is a new version which guards against this exception in all 3 instances
that use the nsIMsgFilter.getActionAt( ) function. 

You should get a suitable error message and some more information in the error
console. Make sure you enable [x]Debug Mode in quickFilters options for full
disclosure.

thanks!

John, you got back to me on email reporting the prerelease was now "working"
(*) can you please give some more context? 

1. what exactly were you doing when it happened? A step-by-step description
would be most helpful.

2. List any additional error console output, best with debug mode enabled. If
you install console2 you can copy/paste them as text (context menu in tools >
error console), which is more helpful. (also with console2: switch on [All] and
then disabled [Content])

3. with the "fixed" version, was a particular filter highlighted as being
problematic? Or removed from the selection when you marked multiple users for
merging.

4. If you could pin point which filter was the culprit, could you check what
its filter action was?

I could add additional debug output to help find out what exactly happened but
it the information above is important to understand what is the cause. Normally
the getActionAt() function should never fail, so either you have some very
esoteric or broken filters, or I lack some understanding that would be vital to
improve quickFilters in the future.

thanks for your cooperation!

(*) just for context: I am dealing with the exception by omitting the offending
filter (and in some cases I display a messagebox), so you should definitely see
a visible change on screen; e.g. a filter being removed from the selection etc.
and also some messages in error console (enable debug mode in qF options)