Trying to open the “Advanced Filter” dialog within Bookcase 0.6.3 from KDE 3.0.x crashes the app. It’s a simple enough fix. Line 46 in src/bcfilterdialog.cpp should read
: QHBox(parent_, name_), m_editRegExp(0), m_editRegExpDialog(0) {
A patch file is available if anyone wants it. This will be included in the next released version, of course.