When bookmarks sidebar is closed the setting should be persistent.

[JFRbates]

If the Bookmarks sidebar is closed (using the X) the setting should be persistent when Firefox is closed and reopened.  Currently a close/reopen cycle makes it reappear even though the sidebar was closed when Firefox was closed.

[Jon]

Thanks for submitting an idea to the Mozilla Connect community! Your idea is now open to votes (aka kudos) and comments.

[joeytwiddle]

My bookmarks sidebar doesn't open when I open Firefox. 

Perhaps try with a fresh profile to see if this behaviour is actually just a problem with your current profile.

[thermion]

Whose bright idea was it to cause View.Sidebar to deselect a user choice after exiting Firefox? I use the bookmarks constantly, and it is an inconvenience to have to keep toggling them back on again. It takes away most of the purpose of the "View" option.