If you use Libreoffice in Windows 7 (probably in other Windows too) and select some sheets in Calc the selection is nearly not recognizable because they are both pretty bright. Maybe there is a slight difference but it is nearly impossible to notice on a bright flat screen. This problem doesn't appear in Linux because the unselected sheets are gray while the selected ones are white.
[Reproducible] with "LibreOffice 3.3.1 RC1 - WIN7 Home Premium (64bit) German UI [OOO330m19 (build 7 / tag 3.3.1.1)]". It's the same with the Layer tabs in DRAW Enhancement!
[This is an automated message.] This bug was filed before the changes to Bugzilla on 2011-10-16. Thus it started right out as NEW without ever being explicitly confirmed. The bug is changed to state NEEDINFO for this reason. To move this bug from NEEDINFO back to NEW please check if the bug still persists with the 3.5.0 beta1 or beta2 prereleases. Details on how to test the 3.5.0 beta1 can be found at: http://wiki.documentfoundation.org/QA/BugHunting_Session_3.5.0.-1 more detail on this bulk operation: http://nabble.documentfoundation.org/RFC-Operation-Spamzilla-tp3607474p3607474.html
This is still an issue in 3.5.0 Beta 2.
Still a problem in 5.3.3.2 on Windows 10.
*** Bug 86136 has been marked as a duplicate of this bug. ***
*** Bug 96853 has been marked as a duplicate of this bug. ***
I mark this as the duplicate of the newer bug as there is more discussion about better visibility. *** This bug has been marked as a duplicate of bug 104564 ***