- handle space and enter in zotero pane to always click on toolbarbutton.
It ensures consistent behavior across all components to avoid Enter
triggering click on some buttons but not others.
- address the issue of focus not being able to leave the reader once it
gets there. On Escape, when reader is opened, instead of re-focusing the reader,
focus the selected tab. From there, Enter will focus the reader, and tabbing
allows you to reach the itemPane.
- Tab/Shift-tab moves focus between Sync button and itemPane when
reader is opened
