Hello Meir,
I think you have customized the main menu, but you will see these workspace comamnds if you reset the main menu (Tools > Customize Menus).
Also, the new workspace feature has no interaction with the Projects plug-in. When you mention ‘solutions’ or ‘projects’, I suspect those are related to the Projects plug-in, but workspaces have nothing to do with the Projects plug-in. A workspace can include multiple group windows. Therefore, I didn’t allow multiple workspaces appear at the same time.
Thank you for trying the beta version!