ohif-viewer/LesionTracker/client/components/viewerSection/viewerSection.js

Template.viewerSection.events({
     'transitionend .sidebarMenu'(event) {
         if (!event.target.classList.contains('sidebarMenu')) {
             return;
         }
 
         handleResize();
     }
 });

Template.viewerSection.helpers({
    leftSidebarOpen() {
       return Template.instance().data.state.get('leftSidebar');
    },

    rightSidebarOpen() {
       return Template.instance().data.state.get('rightSidebar');
    }
});