3.6.3

* Cancel the visual gap of the sidebar contents when visibility of Firefox's toolbar is toggled for some special cases: about [the bookmarks toolbar for new tabs on Firefox 84 and later](https://bugzilla.mozilla.org/show_bug.cgi?id=727668), and about the navigation toolbar in the fullscreen mode. You can access invisible tabs top of the sidebar with hovering on the top edge of the sidebar contents.
* Context menu commands "Close Other Tabs" and "Close Tabs to Bottom" now don't close hidden tabs like Firefox's native commands.
* Better compatibility with other addons around tabs moved across windows by other players like [Simple Tab Groups](https://addons.mozilla.org/firefox/addon/simple-tab-groups/). TST now don't clear `openerTabId` of such tabs.
* Better response for F1 key or the toolbar button to toggle the sidebar on Firefox 73 and later.
* Reduce the timeout to kill zombie connections for an already closed sidebar, from 5 seconds to 0.5 seconds.
* Restore tree strucutre correctly for a tab which was a parent and reopened via Ctrl-Shift-T.
* Network error pages now have the warning favicon rendered with visible color, like Firefox's native tabs.
* No drag session is started anymore for tabs when `Do nothing / Do nothing` is chosen for the drag action.
* Prevent starting of accidental drag sessions for clicked tabs from Firefox's bugs around IPC more aggressively.
* Create bookmarks to the bookmarks toolbar by default like Firefox 84 and later.
* Guide to click the button in a desktop notification with the phrase "click the button" instead of "click here", on Linux environment.
* Avoid losing the cusror position of the input field for the user styles while typing, more certainly.
* Scroll the sidebar to newly opened tabs even if animation effects are disabled. (regression on 3.5.33)
* Indicate new tabs opened outside of the visible area with blue flash even if animation effects are disabled. (regression on 3.5.33)