Hi Ludek,
I just installed SP8 and tested this issue and can report that it is mostly fixed.
There are however 2 issues that remain:
1. The "Go to First Page" and "Go to Last Page" buttons are always disabled.
2. If you have a long running report and you move to another TAB while it is running, when you come back after it has finished all of the controls remain disabled. It looks like the fix that was made only works if the report is visible when it finishes running.
Thanks
Anthony