Revise "Hide/Show Sidebar" toggle as "Collapse/Expand Sidebar" for the new Vertical Tabs feature

[ladyKiller]

The “Hide/Show Sidebar” toggle with the Control ⌃ + Z hotkey on macOS is a great setting; however, I believe it would be much more useful if it collapsed the sidebar into tab icons so that we can quickly hide the tab names and allocate more free space for the webpage as needed.

The “Expand sidebar on hover” setting in the sidebar settings already does that job in an elegant way; however, it often glitches and stops working as expected, or becomes stuck in the collapsed state. This usually happens over time as you switch or open more and more tabs, and it resolves automatically after reopening the Firefox app. I suspect it could be related to an animation glitch (from the expand/collapse transition) or a corrupted/cluttered memory issue that affects Firefox’s internal state.

Anyway, this issue was annoying enough that I had to disable the hover setting and reduce the size of the sidebar to make it just large enough for reading the tab names, so that I don’t have to hide the sidebar every time I switch to a different tab.

I believe both the “Hide/Show Sidebar” toggle button on the toolbar and the hotkey would be much more useful if they collapsed the sidebar rather than hiding it completely; hence, I wanted to share my user experience as feedback.

Firefox

[Jon]

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