・Middle/Right click default bookmarks/history tool-button.
・Click the additional toolbar-button which can be arranged by using Customize toolbar.
・You change popup in a bookmark / history from an icon in the top right corner of the popup, and change the popup into sidebar.
・You can change size of popup by dragging resizer at the bottom right corner.
・The popup size of bookmark and history is retained respectively.
・A pop-up scroll state and the selection state of an item are retained within sessions.
・The folder which is not used can be closed automatically. (When it clicks except the expander mark.)
・Shortcut key added for toggle panel. Accel+Alt+Shift+B, Accel+Alt+Shift+H, for the moment, these cannot be customized -- however, it can change by using Keyconfig extension.
If you want to popup another sidebar, use sidebar popup panel https://addons.mozilla.org/en-US/firefox/addon/sidebar-popup-panel/