In the administration interface if you click the "new class group" button it instantly creates a "New group" Content Type Group regarding of pressing OK or not.
- log in administration interface
- go to classes page (/class/grouplist)
- click "New class group"
- verify on URL the ID of the group that is being created
- through URL go to classes page (/class/grouplist)
- verify that there is a "New group" group
- and verify the ID is the same of the one that was being created before
Even if pressing "Cancel" it creates the group