function SetActiveDialog(oWnd)
{
    window.activeDialog = oWnd;
}

function GetActiveDialog()
{
    if (window.activeDialog) 
        return window.activeDialog;
    if (window.frameElement.activeDialog) 
        return window.frameElement.activeDialog;
    
    var parentWindow = window.parent;
    while (parentWindow != null)
    {
        if (parentWindow.activeDialog) 
            return parentWindow.activeDialog;
        parentWindow = parentWindow.parent;
    }

    return null;
}

function CloseActiveDialog(returnValue)
{
    var oWindow = GetActiveDialog();
    oWindow.Close(returnValue);
}