Dock relies on receiving notifications from WindowServer as apps and windows are created and destroyed. If Dock restarts, it only has the persistent items from preferences, leaving no way to restore minimized or hidden windows. Cmd-Tab to switch apps then choosing hidden menus from the Windows menu might work, but let's make Dock poll WS for a list of apps at startup and create the necessary tiles to show accurate state.

This will need a new RPC in WindowServer.