empty windows

[Guy Maurel]

Hello!

I get many empty windows, look at https://bugs.kde.org/show_bug.cgi?id=320966
to see 3 of them.

I identify the source code where the problem occurs (using kmail, Settings, 
Configure Kmail):

within kdelibs/kdecore/sycoca/ksycocadict.cpp
540 qint32 KSycocaDict::Private::offsetForKey(
...
at line
560    (*stream) >> retOffset;

retOffset is set to zero.

Running kbuildsycoca4 at a konsole, the problem seems to be away.

Any help, where to look after?
Are there any check for the coca-database?
Thanks
-- 
guy