On startup, if any sharing is enabled, gnome-user-share will be started and stay running. If nothing is enabled, it will start and immediately exit. The sharing panel should make sure that gnome-user-share gets started if it isn't already.

This should be solvable in gnome-user-share using a startup condition:
$ grep -i condition /etc/xdg/autostart/*
/etc/xdg/autostart/at-spi-dbus-bus.desktop:AutostartCondition=GSETTINGS org.gnome.desktop.interface toolkit-accessibility
/etc/xdg/autostart/caribou-autostart.desktop:AutostartCondition=GSettings org.gnome.desktop.a11y.applications screen-keyboard-enabled
/etc/xdg/autostart/nautilus-autostart.desktop:AutostartCondition=GSettings org.gnome.desktop.background show-desktop-icons
/etc/xdg/autostart/orca-autostart.desktop:AutostartCondition=GSettings org.gnome.desktop.a11y.applications screen-reader-enabled
/etc/xdg/autostart/vino-server.desktop:AutostartCondition=GSettings org.gnome.Vino enabled

But gnome-user-share doesn't have a single condition. I'd need to check whether we can make it have one, or whether gnome-session supports multiple autostart conditions, or, finally, have the control-center panel start it.

You can't have multiple conditions.
You could either add a separate 'should I be running' boolean and use that as the master switch, or indeed, have the control-center start it.

We should fix this for 3.8.3 - it makes the sharing panel pretty limited use.

Created attachment 246726 [details] [review]
data: Fix turning on sharing not starting gnome-user-share

Use AutostartConditions in the desktop file to get gnome-user-share
to start if either ObexFTP, ObexPush or WebDAV sharing is enabled.

Comment on attachment 246726 [details] [review]
data: Fix turning on sharing not starting gnome-user-share

Fixed in 3.8.3