SQL Editor: more than one long query (3 replies)

while executing a long query, i can't start another query in a second query-tab on the connected server. The buttons "Execute SQL Script.." and "Execute current SQL Statement.." are disabled.

Workbench: 5.2.34 CE Revision 7780
OS: Windows XP Professional SP3
MySQL: 5,5,8 on Linux x86_64