extjs4.0tree滚动条bug修复

// Override Ext.grid.Scroller object
// to workaround ExtJS bug EXTJSIV-3770
// more info at http://www.sencha.com/forum/showthread.php?142473-Bug-Tree-Grid-Scroller-Stops-Working
Ext.override(Ext.grid.Scroller, {

  afterRender: function() {
    var me = this;
    me.callParent();
    me.mon(me.scrollEl, 'scroll', me.onElScroll, me);
    Ext.cache[me.el.id].skipGarbageCollection = true;
    // add another scroll event listener to check, if main listeners is active
    $(me.scrollEl.dom).scroll({scope: me}, me.onElScrollCheck);
  },

  // flag to check, if main listeners is active
  wasScrolled: false,

  // synchronize the scroller with the bound gridviews
  onElScroll: function(event, target) {
    this.wasScrolled = true; // change flag -> show that listener is alive
    this.fireEvent('bodyscroll', event, target);
  },

  // executes just after main scroll event listener and check flag state
  onElScrollCheck: function(event, target) {
    var me = event.data.scope;
    if (!me.wasScrolled)
      // Achtung! Event listener was disappeared, so we'll add it again
      me.mon(me.scrollEl, 'scroll', me.onElScroll, me);
    me.wasScrolled = false; // change flag to initial value
  }

});

















Ext.override(Ext.grid.Scroller, {

  afterRender: function() {
    var me = this;
    me.callParent();
    me.mon(me.scrollEl, 'scroll', me.onElScroll, me);
    Ext.cache[me.el.id].skipGarbageCollection = true;
    // add another scroll event listener to check, if main listeners is active
    Ext.EventManager.addListener(me.scrollEl, 'scroll', me.onElScrollCheck, me);
    // ensure this listener doesn't get removed
    Ext.cache[me.scrollEl.id].skipGarbageCollection = true;
  },

  // flag to check, if main listeners is active
  wasScrolled: false,

  // synchronize the scroller with the bound gridviews
  onElScroll: function(event, target) {
    this.wasScrolled = true; // change flag -> show that listener is alive
    this.fireEvent('bodyscroll', event, target);
  },

  // executes just after main scroll event listener and check flag state
  onElScrollCheck: function(event, target, options) {
    var me = this;

    if (!me.wasScrolled) {
      // Achtung! Event listener was disappeared, so we'll add it again
      me.mon(me.scrollEl, 'scroll', me.onElScroll, me);
    }
    me.wasScrolled = false; // change flag to initial value
  }

});