When clicking "com.github.gwtbootstrap.client.ui.Button" in Internet Explorer (I tested version 9, 10 and 11) GWT raises an event that makes it call the "mayStop" method in "com.google.gwt.activity.shared.Activity"s.
I have to completly remove the "href" attribute from the Button element to prevent this behavior. By default the button contains href="javascript:;" which should be removed as long as no href value is assigned.