i lost the targeted block everytime ive broken a multiblock structur.
i got every other block always back.

tried to reproduce it and tried to use other tools for breaking - same results.

I can confirm this happened to me also, my 'contribution' is in my other bug report.. With which I can't even play MC..

We have over 4400 issues, I can assure you that we don't remember "your other bug report".

File the issue properly, using the issue template, or you will not receive assistance.

Please read the contributing guidelines and add the information requested there. Currently your report does not even mention what version of Minecraft you are using, which would be very important information for fixing this. I also do not believe that it happens with just IE (that would have been reported before), so a full modlist is necessary.