My instructions are step-by-step: please don't be put off by the number of steps. It will only take 2 minutes.
If you have, for example, ProjectA set up in MLO as a project (make sure the "Project" box is ticked in the Project parameters on the right column) then this is what I would do:
1. Add a new tab (click the '+' at the right of the tabs)
2. Immediately name it (Project A)
3. Don't sync (leave the check boxes for syncing un-checked)
4. Expand the 'Filter' options from the left hand column (at the bottom under views)
5. You will see all the filter options listed. The one you want is 'advanced'
6. Click advanced and then "setup"
7. "Add Rule"
8. Choose "ProjectName" from the first drop down
9. Choose "Contains" or "Is" from the second
10. Type "ProjectA" in the final box
11. Click OK
12. Optional: Click the "Zoom-in" icon from the taskbar (to the right of the sync button). This will make it 'hide' the top level (parent tasks of the project)
13. Optional: Right click the tab name and "Set As Default For This Tab". This means that if you make changes to the layout by accident you can restore back to this view.
Good luck