Workaround: 

Telerik.Web.UI.RadToolBar.Views.Lite.prototype._repaint = function () {
    this._updateItemsTextAndImage();
    this._showAllHiddenItems();
    if (this._owner.get_orientation() == Telerik.Web.UI.Orientation.Horizontal) {
        this._responsiveCheck();
    }
}

KeyboardNavigationSetting property Activated does not work, when set to True:
- JavaScript error thrown when KeyboardNavigationSetting Activated is set to true in Classic render mode.
- Nothing happens in Lightweight render mode.

For the time being you can use the ApplicationMenu withing the RadRibbonBar control.

Hello,

I found issue that RibbonBarClickableItem has not specified UrlProperty attribute for DisabledImageUrl and DisabledImageUrlLarge properties

So when I'm using relative url path in skin files the computed url is wrong. It is relative to path where control is used instead of relative in theme folder.

Thanks Vlad