Log out all tabs when logging out of an APM Webtop

How can we cause each tab launched from a Webtop move to the logout page when the user logs out of the Webtop with the Logout button?

Right now, if the user logs out of the webtop, the APM session is closed as expected, but each tab is sitting where it was before and appears to still be an active session. When the user attempts to navigate within the tab, the app page fails ungracefully (timeout, etc.), leaving the user in a confused state.

It used to automatically transition most tabs to logout.php3, but we were making changes to SSO, among other things, and it stopped. Even when it worked, it was inconsistent between applications, so it seems likely that the issue was specific to the Portal Access resource item configuration, but we can't find it.

I would like anything that causes the APM session to terminate (logout URI detection, ACCESS::closed, etc.) to behave this way.