Implement a transient webpage sidebar feature (similar to Firefox Side View)

[win8linux]

As an alternative to fixing #646, the functionality of Firefox Side View extension could be reimplemented into Floorp itself instead. While it is already possible to create a Web Panel, this is more permanent and takes more steps than what Firefox Side View provides.

[CutterKnife]

Thank you for your idea.
One immediate means is the Split View feature. Right-click on the tab and select it from the menu.

[win8linux]

This is close, however it still requires that a tab be present and it is not resizable. Perhaps it could be expanded or changed to work closer to Mozilla's FF Side View, but better integrated into Floorp's sidebar?