Qt Installer framework hide or disable buttons

[lanka]

HI,
I want to hide or freeze the back button on a page ( to be more specific, License Agreement Page). I tried editing control.qs with few methods but it doesn't seems to work. Following is one of them

Controller.prototype.LicenseAgreementPageCallback = function()
{
    var widget = gui.currentPageWidget();
    if (widget != null) 
    {
        widget.BackButton.setVisible(false) ;
    }
}