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Seems that the current event handlers attached to the scroll buttons do not detect the mouseup/touchend events.
Possible workaround would be to attach an event handler to the document directly.
<script type="text/javascript">
$(document).on('mouseup touchend', function (e) {
var tabStrip = $telerik.findControl(document, 'RadTabStrip1');
if(typeof tabStrip !== 'undefined'){
tabStrip._scroller._stopScroll();
}
});
</script>