extjs gridpanel inside a panel not autoscroll or resize - extjs

Question

I have a tabpanel. In the tab, i have a panel which includes a toolbar and 3 items: [ fieldset, a gridpanel, and another fieldset (or some buttons)]. I cannot get the gridpanel to show scroll bar. It only works if i set the maxheight/minheight of the gridpanel.
I also tried wrapping gridpanel inside a container. No luck.
In the example, i use fit layout. I tried "anchor" layout, and assigned anchor:'100% 50%' to gridpanel, hoping that it would resize when i resize browser. No luck.
Alternatively, if gridpanel is the ONLY item in the tab, autoscroll would work. So it appears when it's inside another panel, autoscroll/ resizing does not work.
Did I miss something here ?
Ext.application({
name: 'MyApp',
launch: function () {
// create the data store
var d = ['company', 100];
var myData = [];
for (var i = 0; i < 50; i++) {
myData[i] = d;
}
var store = Ext.create('Ext.data.ArrayStore', {
fields: [{
name: 'company'
}, {
name: 'price',
type: 'float'
}],
data: myData
});
Ext.create("Ext.container.Viewport", {
layout: {
type: 'border'
},
items: [{
xtype: 'toolbar',
id: 'headerbar',
region: 'north',
height: 30
}, {
xtype: 'toolbar',
id: 'menubar',
region: 'north',
height: 30
}, {
xtype: 'tabpanel',
itemId: 'maintabpanel',
activeTab: 0,
region: 'center',
plain: true,
margins: '5 5 5 5',
layout: 'fit',
items: [{
closable: false,
title: 'Tab',
margins: '0 0 0 0',
items: [{
xtype: 'panel',
title: 'Panel',
layout: 'fit',
tools: [{
type: 'help',
tooltip: 'Help'
}, {
type: 'close',
tooltip: 'Close'
}],
items: [{
xtype: 'fieldset',
title: 'Field Set',
layout: 'hbox',
items: [{
xtype: 'textfield',
fieldLabel: 'Input'
}]
}, {
xtype: 'gridpanel',
autoScroll: true,
store: store,
columns: [{
text: 'Company',
flex: 1,
sortable: true,
dataIndex: 'company'
}, {
text: 'Price',
flex: 1,
sortable: true,
dataIndex: 'price'
}],
viewConfig: {
autoFit: true
}
}, {
xtype: 'fieldset',
title: 'Field Set 2',
layout: 'hbox',
items: [{
xtype: 'textfield',
fieldLabel: 'Output'
}]
}]
}]
}]
}, {
xtype: 'box',
id: 'footer',
region: 'south',
html: '<h1> Copyright 2012</h1>',
height: 30
}]
});
}
});

Answer 1

Note that the parent panel of the gridpanel has fit layout, yet it has more than 1 item (the fieldset, the gridpanel, and another fieldset). A fit layout can only have 1 child.
Also, the parent of that fit panel (the one with closable : false - the tab) has no layout definition.
Here's a JsFiddle modified version of your code that works.