whether a sheet is registered. Bug 286518, patch by Ted Mielczarek (luser) <ted.mielczarek@gmail.com>, r+sr=bzbarsky git-svn-id: svn://10.0.0.236/trunk@171031 18797224-902f-48f8-a5cc-f745e15eee43
git-svn-id: svn://10.0.0.236/trunk@167752 18797224-902f-48f8-a5cc-f745e15eee43