Sidebar Tabs por asamuzaK

Emulate tabs in sidebar and...
* display tabs vertically.
* group tabs and collapse / expand them.

# about:config

Experimental features are used, so you need to activate the following.

* Set `svg.context-properties.content.enabled` to `true`.

# Tab group

* Select tabs by "Shift + left click" or "Ctrl + left click" ("Cmd + left click" on Mac) on each tab.
* Drag one of the selected tabs with "Shift + left click" and drop it on the tab you want to group.
* You can also group tabs by selecting "Tab Group" from the context menu and selecting "Group Selected Tabs".
* Tab groups are color-coded for each.
* Collapse / expand tab groups can be done by clicking on the colored part, or from the context menu.
* The new tab opened from the tab in the tab group will be displayed as the tab of that group.
* To cancel the grouping of tabs, you can do it from the context menu.
* Tab groups will not be saved during private browsing.