Unable to focus tab bar using keyboard

Steps to reproduce:

• Create a minimal window with a widget like a button and a tab bar with some tabs
• Optionally add a buttonbox with OK and Cancel buttons (not necessary for reproduction)
• Use tab key to switch bitween widgets

Actual behavior:

• You can't access tab bar and buttonbox if present. If you focus tab bar with CTRL+Tab, you can't go out of the tab bar

Expected behavior:

• We should be able to access tab bar and all widgets using tab key, like previously.