* make sure you are using xulrunner 1.9.2 or higher
 * launch with conkeror -q
 * C-x C-f "google foo" return
 * wait for google to finish loading
 * q (close the new buffer)
 * C-x C-f "google foo" return
 * wait for google to finish loading
 * use a window-manager key to switch workspaces or resize the window
 * conkeror no longer responds to keyboard events.
 * to get focus back, click or run "conkeror -f unfocus"

The basic procedure is, kill a buffer, create a buffer, perform a
window-management action.  But the problem can be produced in other
circumstances, too.  I narrowed it down to the subsystem which tracks
element/frame focus after using the minibuffer or killing a buffer.  The
point of failure is at calls to set_focus_no_scroll.

as of xulrunner 1.9.2, conkeror's element/frame focus tracking is no longer necessary.  What is necessary
is to focus the xul:browser when we exit the minibuffer or kill a buffer.  Note that the element/frame
focus tracking system must be retained for compatibility with older versions of xulrunner.  That code can
be removed if we ever drop support for xulrunner 1.9.1.