Stop all Events (preventDefault) an Ext Window when Show window.setVisible(true)

[equiman]

This problem is related to this subject:
http://forums.ext.net/showthread.php...ountdown-alert

I have a Window that is Hidden. In a moment I change the visibility using

frmTimeOut.setVisible(true);

But when Show the window.. then it launch an event and is detected by the browser (probed wit IE, FF, GC) as "mouseover".
I'm trying to prevent this event adding this to Window:

    <Listeners>
        <Show PreventDefault="true" />
    </Listeners>

Or with this:

<Listeners>
        <Show StopPropagation="true" />
    </Listeners>

But the browser steel detecting as "mouseover" event.

How can I use .stopPropagation ( ); or preventDefault(); when the window is showing?