6576: Set custom pango markup can generate GtkWarning, ValueError or TypeError

git-svn-id: svn+ssh://svn.code.sf.net/p/gramps/code/branches/maintenance/gramps40@22143 4ae1f11a-8b86-4847-b8af-ab372f36d1fd
6656: division on hexadecimalcolor

git-svn-id: svn+ssh://svn.code.sf.net/p/gramps/code/branches/maintenance/gramps40@22145 4ae1f11a-8b86-4847-b8af-ab372f36d1fd
6668: number of arguments for notify_db_error() into Export assistant

git-svn-id: svn+ssh://svn.code.sf.net/p/gramps/code/branches/maintenance/gramps40@22147 4ae1f11a-8b86-4847-b8af-ab372f36d1fd