In the tabpanel of ExtJS 4, how to catch the tabchange event anytime I click a tab?

Question

For each tab in the tabpanel, I have one floating panel located in a fixed spot. When I switch the tabs, I need to bring the corresponding floating panel to the front. However, the tabchange event is fired only the first time. How can I catch this tabchange or other similar event when I click a tab?

Alexey, Here is my example code with more specific questions:

Ext.onReady(function() {
    panel1 = Ext.create('Ext.panel.Panel', {
        title: 'title1', width: 800, height: 50,
        listeners: { 'beforeshow': { fn: function() { 
            console.log("beforeshow on title1"); 
        }, scope: this, single: true } }
    });
    panel2 = Ext.create('Ext.panel.Panel', {
        title: 'title2', width: 800, height: 50,
        listeners: { 'beforeshow': { fn: function() { 
            console.log("beforeshow on title2"); 
        }, scope: this, single: true } }
    });
    panel3 = Ext.create('Ext.panel.Panel', {
        title: 'title3', width: 800, height: 50,
        listeners: { 'beforeshow': { fn: function() { 
            console.log("beforeshow on title3"); 
        }, scope: this, single: true } }
    });
    var tabpanel = Ext.createWidget('tabpanel', {
        renderTo: document.body,
        activeTab: 0,
        width: 800, height: 50, plain: true,
        items: [panel1, panel2, panel3],
        listeners: {
            'tabchange': { fn: function() {
                 console.log("tabchange");
            }, scope: this, single: true }
        }
    });
});

The "tabchange" message just prints once. What I really want is to show the message "beforeshow on ..." everytime I click a tab.

Leoh, you are the man! It turned out the problem in my code is the "fn". The following code works perfectly by removing "fn", "scope", and "single". I don't know why though. Can anybody explain?

Ext.onReady(function() {
    panel1 = Ext.create('Ext.panel.Panel', {
      title: 'title1', width: 800, height: 50,
      listeners: { 'beforeshow': function() { console.log("beforeshow on title1"); } }
    });

    panel2 = Ext.create('Ext.panel.Panel', {
      title: 'title2', width: 800, height: 50,
      listeners: { 'beforeshow': function() { console.log("beforeshow on title2"); } }
    });

    panel3 = Ext.create('Ext.panel.Panel', {
      title: 'title3', width: 800, height: 50,
      listeners: { 'beforeshow': function() { console.log("beforeshow on title3"); } }
    });

  var tabpanel = Ext.createWidget('tabpanel', {
    renderTo: document.body,
    activeTab: 0,
    width: 800,
    height: 50,
    plain: true,
    items: [panel1, panel2, panel3],
    listeners: {
        'tabchange': function() {
             console.log("tabchange");
        }
    }
  });
});

Answer 1

Please attached a function to event tabchange

Ext.onReady(function () {
    panel1 = Ext.create('Ext.panel.Panel', {
        title: 'title1'


    });
    panel2 = Ext.create('Ext.panel.Panel', {
        title: 'title2'

    });
    panel3 = Ext.create('Ext.panel.Panel', {
        title: 'title3'

    });
    var tabpanel = Ext.createWidget('tabpanel', {
        renderTo: document.body,
        activeTab: 0,
        width: 800,
        height: 50,
        plain: true,
        items: [panel1, panel2, panel3],
        listeners: {
            'tabchange': function (tabPanel, tab) {
                console.log(tabPanel.id + ' ' + tab.id);
            }
        }
    });
});

Live Demo Here