Unfortunately, the latest version of WebMenuBar MenuCommand default behavior must be clicked in order to open up. A workaround, by simulating the onClick event during mouse over can be achieved using this snippet:

var id = "";
    
function init()
{
    setTimeout(function()
    {
        var menuBar = ISGetObject("WebMenuBar1");

        for (var i = 0; i < menuBar.Menus.length; i++)
        {
            Listener.Add(menuBar.Menus[i]._HtmlObj, "onmouseover", showMenuCommand, menuBar.Menus[i]);
        }
    }, 500);
}

function showMenuCommand()
{
    if (id != this.Name)
    {
        id = this.Name;
        this.OnClick();
    }
}

The Init() function should be invoked during window onload client side event.

Thanks, Glenn. That did the trick. I did modify it slightly for our scenario where some MenuCommands may have children and some may be a direct link. We want the MenuCommands with a link to actually be clicked and not trigger on mouseover.

                if (menuBar.Menus[i].TargetURL == null) {
                    Listener.Add(menuBar.Menus[i]._HtmlObj, "onmouseover", showMenuCommand, menuBar.Menus[i]);
                }