Responsive HTML5 in-context help broken after upgrade to 11.03.268

Responsive HTML5 in-context help links using robohelp_csh.js and the following function no longer work following upgrading to 11.0.3.

The correct html page is displayed. The contents and index are displayed but are unresponsive and you can't navigate to other pages.

var HH_DISPLAY_TOPIC = 0;
var HH_DISPLAY_TOC = 1;
var HH_DISPLAY_INDEX = 2;
var HH_DISPLAY_SEARCH = 3;
var HH_HELP_CONTEXT = 15;

function RH_ShowHelp(hParent, a_pszHelpFile, uCommand, dwData)
{
// this function only support WebHelp
var strHelpPath = a_pszHelpFile;
var strWnd = "";
var nPos = a_pszHelpFile.indexOf(">");
if (nPos != -1)
{
  strHelpPath = a_pszHelpFile.substring(0, nPos);
  strWnd = a_pszHelpFile.substring(nPos+1);
}

    RH_ShowWebHelp(hParent, strHelpPath, strWnd, uCommand, dwData);
}

 
function RH_ShowWebHelp(hParent, strHelpPath, strWnd, uCommand, dwData)
{
// hParent never used.
ShowWebHelp(strHelpPath, strWnd, uCommand, dwData);
}

function ShowWebHelp(strHelpPath, strWnd, uCommand, nMapId)
{
var a_pszHelpFile = "";
if (uCommand == HH_HELP_CONTEXT)
{
  a_pszHelpFile = strHelpPath + "?rhcsh=1&rhmapno="+ nMapId +"&rhnewwnd=0";
       
        // Note: On IE, specifing the help window causes a blank intermediate window to open,
        // which fails to close.  To prevent that we don't bother specifing the window any more.

        //if (strWnd) {
        //    a_pszHelpFile += "&rhwnd=" + strWnd;
        //}
}

if (a_pszHelpFile)
{
        var leftPosition,topPosition, height, width;

        width = window.screen.width * 0.8;
        height = window.screen.height* 0.8;
        leftPosition = window.screen.width * 0.1;
        topPosition = window.screen.height * 0.1;

  var sParam = "left="+leftPosition+", top="+topPosition+", width="+width+", height="+height+", resizable=yes";
  window.open(a_pszHelpFile, "__webCshStub", sParam);
}
}