open sidebar

[Fil]

Open questions:

• apply to the cli website or not?
• don't let a locally stored preference close a menu that contains the current path?

Done:

• closes Sidebar sections should open automatically when a page within is active #159
• closes Remember which panels are open or closed in the nav #181
• fix the annoying flash on load

[Fil]

Whether we want to apply it to the cli documentation is debatable; I've applied it here so it's easier to test.

[Fil]

There's a bit of a conflict when you have manually closed a section, then go to a page that belongs to that section. In that case should the section be open (as in #159) or closed (as in #181)?
Currently it's closed, but we might want to give priority to opening?

[mbostock]

If you navigate to a page, the section should be open even if you previously closed it; #159 is higher priority than #181.

[mbostock]

There’s a related problem here when the sidebar is taller than the window: when you navigate to a page, the sidebar scrolls to the top. The most natural solution would be to use client-side navigation, which would also solve the problem of remembering which sections are open or closed. But to continue the path in this PR, perhaps we could also stash the scroll offset of the sidebar prior to navigating, so that we can restore it when the next page loads?

This also makes me realize that we should be using sessionStorage instead of localStorage to track which sections are open or closed — you only want it to affect the current tab, not other windows you may have open.

[mbostock]

We can add scroll persistence in a followup PR.

[mbostock]

Oops, we shouldn’t piggyback on the mousedown event here. We should listen for the toggle event on the parent details instead. I’ll fix.

[Fil]

fixed in 83ef581

followup 4434cd0

(thank you!)