Hi, there was an improvement added a while back here http://www.sencha.com/forum/showthre...s-Tab&p=734587
but this does not seem to work.
How to repeat: use "Advances Tabs" example, add couple of closeable tabs using the button provided, close them one by one. Note: "Tab 1" will be active after every time you close another tab 
As i outlined in the aforementioned thread, this can be fixed with this code:
Code:
Ext.override(Ext.tab.Bar, {
setActiveTab: function(tab) {
if (tab.disabled) {
return;
}
var me = this;
if (me.activeTab) {
//if( tab !== me.items.first() ) me.previousTab = me.activeTab; //changed here
me.activeTab.deactivate();
}
tab.activate();
me.activeTab = tab;
me.fireEvent('change', me, tab, tab.card);
},
onAdd: function(tab) {
var me = this;
me.previousTab = tab;//added here
tab.position = this.dock;
this.callParent(arguments);
},
onRemove: function(tab) {
var me = this;
if (tab === me.previousTab) {
//me.previousTab = null; //changed here
me.previousTab = me.items.last();//added here
}
if (tab === me.activeTab) {
me.activeTab = null;
}
if (me.items.getCount() === 0) {
me.activeTab = null;
}
me.callParent(arguments);
}
});