JSFiddle - React, Tailwind, and code Playground

HTML

<link rel="stylesheet" href="http://dev.sencha.com/deploy/ext-4.0.2a/resources/css/ext-all.css">
<input type="button" onclick="elegir()" value="tocame">

JavaScript

var menuOpcionesUsuario = new Ext.menu.Menu( {
    id: 'menuOpcionesUsuario',
    //title: 'opciones',
    margin: '0 0 10 0',
    plain: true, //elimina separador
    //defaults:{  
    //  iconAlign: 'top' // <--- we change the icon position  
    //},
    data:{
        idSubmenu : 0	
    },
    floating: true,
    listeners: {
        render: function(ventana) {

        },
        beforeshow: function(ventana) {
 
        },
        beforehide: function(ventana){

        }
    },	
    items: [
    {
        text: 'Cambiar de Reparticion',  
        iconCls:'menu_house_1',  
        handler: function(){
		
            ventanaCambiarRepart.show();
			
        }
    }]
});



var store = Ext.create('Ext.data.TreeStore', {
    root: {
        expanded: true,
        children: [
            { text: "detention", id:'item_1', cls:'doc_3', leaf: true },
            { text: "homework", id:'item_2', expanded: true, children: [
                { text: "book report", id:'item_3', checked:true, leaf: true },
                { text: "alegrbra", id:'item_4', leaf: true}
            ] },
            { text: "buy lottery tickets", id:'item_5', leaf: true }
        ]
    }
});

Ext.create('Ext.tree.Panel', {
    title: 'Simple Tree',
    id:'tree-panel',
    width: 200,
    height: 200,
    store: store,
    autoScroll: true,
    //rootVisible: false,
    renderTo: Ext.getBody(),
    listeners: {

        render: function() {
            Ext.getBody().on("contextmenu", Ext.emptyFn, null, {preventDefault: true});
        },
          itemcontextmenu : function( grid, record, item, index, event){
              x = event.browserEvent.clientX;
              y = event.browserEvent.clientY;
              console.log(record,item)
              menuOpcionesUsuario.showAt([x, y]);
              
              
          }
      }
});

var tree = Ext.getCmp('tree-panel');
tree.getSelectionModel().select(3);

//console.log(Ext.getCmp('item_3'))

function elegir(){
    var TreeNodeId =...