Another solution is to switch the ItemTemplate to a ContentTemplate. The desired functionality is achieved. However when you set an item to a ContentTemplate the item can have no child items so it may not be a solution for every scenario.
It's a typo and is fixed now, thank you for spotting it.
is rmTempalte in your code miss spelled or correct?
Workaround: <script type="text/javascript"> Telerik.Web.UI.RadMenu.prototype._onLinkMouseUp = function (e) { var item = this._extractItemFromDomElement(e.eventMapTarget); if (!item.get_enabled()) { return true; } if (Telerik.Web.Browser.chrome || Telerik.Web.Browser.ie || Telerik.Web.Browser.edge) { this._preventBlurEvent = true; if (!$(e.eventMapTarget).has("rmTemplate")) { this.focus(); } } item._clicked = false; item._updateLinkClass(); item._updateImageSrc(); return true; } </script>