Pr4 UG ui Tab Bar
From Protege Wiki
The Tab Bar selects a set of views to be shown in the Main Window. In general, each tab should contain the views necessary to complete a task. Bouncing between tabs in the middle of a task wastes the user's time; it can also cause errors, due to the mental load (and resulting confusion) it causes.
Fortunately, Protege 4 tabs are extremely configurable. If you find yourself switching between tabs in the middle of a task, consider adding the relevant views to the tab you're using (or creating a new, customized tab for the task).