test

    Steps to reproduce:
    * load this page with js enabled
    * open the JS debugger console
    * set a breakpoint at the start of the window.onmousedown function
    * click on the title - debugger will stop in that function
    * mouseover "zork"

    Observed behaviour:
    JS debugger pane becomes entirely blank and cannot be recovered
    in that tab (other tabs do not seem to be affected)

    Expected behaviour:
    JS debugger shows tooltip for prototype-less Object
    (and does not disappear)