By default View -> Single Document ticked works Ok
When unticked , the top tabs disappear and multiple windows appear , still works all good.

But now if I press maximize button on any of these windows it goes back to single document mode (the Single document ticked), which i think is a bug.

In PLSQLD14 it works fine and I like the way PLSQLD14 works as it frees up the tabbed area for me and I like to use docked window list to navigate between windows.

This is by design. If you do not want the SDI tab pages, go to Preferences > User Interface > Appearance and select "Don't show tabs" under "Settings for Single Document Interface".

ok thanks for the clarification, I managed to get it working based on your instructions.