Multiple admin menu items in "selected" state

[getdave]

Currently on master in Calypso it is possible to end up in a state where multiple admin menu items are in a "selected" state.

This is not inline with the WPAdmin experience.

One fix for this would be to only allow one item to be selected at a time. That's a good idea, however when menus are expanded, removing the selected state causes them to "collapse" which could cause the menu to "jump" around.

A better idea might be to:

• Only allow 1 item to be "selected" at any one time.
• Allow submenus to remain "expanded" even if they aren't selected. This would avoid the layout jumps.

Note that some of the behaviour above is not perceivable on WPAdmin because it uses full page reloads.