Configuring two dashboard pages in different browser tabs leads to page crash

If your dashboard is in configure mode and you have multiple dashboard pages defined, open a different dashboard page in a second browser window/tab (but same browser) and then in the original browser window click one of the portlet move icons (e.g. move up, move down). The page crashes.

This is because the current dashboard page is stored in the session and the portlet move operation gets the portal page from that session.