A Firefox userChrome.js script that brings a second sidebar with web panels like in Vivaldi/Edge/Floorp but better.

I've tried various browsers, such as Vivaldi, Edge, Floorp, and Zen, and they all have one thing in common that I can't imagine using a browser without — the sidebar. Unfortunately, Firefox, which I feel most closely aligns with my needs in terms of spirit and functionality, has a rather unsatisfactory sidebar. Therefore, I decided to create another one myself, with blackjack and hookers!

• Actions: Show • Hide
• Customize via Customize Toolbar...
• Settings:
  • General: Position (Left / Right) • Width
  • Visibility: Auto-hide sidebar • Auto-hide behaiour (Inline / Overlay) • Hide web panel when sidebar is hidden • Set shortcut to hide/show sidebar
  • Web panel: Default floating panel offset • New panel position (Before plus button / After plus button) • Show geometry hint
  • Web panel button: Container indicator (Off / Left / Right / Top / Bottom / Around) • Tooltip (Off / Title / URL / Title and URL) • Show full URL in tooltip
  • Web panel toolbar: Auto-hide forward button • Auto-hide back button
  • Animations: Animate sidebar • Animate web panel toolbar

• Actions: Create • Delete • Edit • Change position and size • Reset position and size • Unload • Mute • Unmute • Pin • Unpin • Change zoom • Go back • Go forward • Reload • Go home
• Extensions support
• Popup notifications support (permissions to use microphone/camera/location, etc.)
• Settings:
  • General: URL • Multi-Account Container • Temporary • Mobile view • Zoom
  • Title: Dynamic • Set static title
  • Favicon: Dynamic • Set static favicon
  • Position and size: Mode (Floating / Pinned) • Always on top • Position anchor • Horizontal offset • Vertical offset • Width • Height
  • Loading: Load into memory at startup • Restore last opened page • Unload from memory after closing • Periodic reload
  • Keyboard shortcut: Set shortcut to hide/show web panel
  • CSS selector: Enable • Set CSS selector
  • Hide elements: Hide toolbar • Hide sound icon • Hide notification badge

• Second Sidebar to show / hide sidebar

1. Install fx-autoconfig.
2. Copy the contents of the src/ directory (second_sidebar/ and second_sidebar.uc.mjs) into chrome/JS/.
3. Enable toolkit.legacyUserProfileCustomizations.stylesheets and dom.allow_scripts_to_close_windows in about:config.
4. Clear startup-cache.
5. Have fun!