@azure08 There is no such thing as "open the workspace in a new window", that's what you seem to be misunderstanding.
Workspaces contain windows that contain tabs. Tabs do not contain window and those do not contain workspaces.
When you start Opera for the first time ever, you are in Workspace 1. More exactly in tab 1 of windows 1 of workspace 1. If you open a new tab, it will be tab 2 of window 1 of WS 1. A new window would be window 2 of WS 1.
If you create a new workspace and go to it, then you will be in tab 1 of window 1 of workspace 2.