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

git-svn-id: svn+ssh://svn.code.sf.net/p/gramps/code/trunk@22144 4ae1f11a-8b86-4847-b8af-ab372f36d1fd
6656: division on hexadecimalcolor

git-svn-id: svn+ssh://svn.code.sf.net/p/gramps/code/trunk@22146 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/trunk@22148 4ae1f11a-8b86-4847-b8af-ab372f36d1fd