• Ctrl+B or Cmd+B on Mac - to toggle the sidebar
• Ctrl+Shift+F or Cmd+Shift+F on Mac - opens and sets the focus strictly on the search tab in the sidebar
• Ctrl+Shift+E or Cmd+Shift+E on Mac - to toggle the focus between the sidebar explorer and the editor window (if your focus is on the search tab, for example, you will first go to the explorer tab, and pressing the combination again will jump to the editor window)
• Ctrl+1 or Cmd+1 on Mac - Set the focus strictly on the editor window

Also, a very useful feature is filtering files on the sidebar Explorer tab:

• Ctrl+Alt+F or Cmd+Alt+F on Mac - to toggle the filter widget in Explorer tab