I write the code below.
    xtype: 'form',
    layout: 'column',
    defaults: {
        border: false,
        layout: 'form'
    items: [{
            autoWidth: true,
            labelWidth: labelWidth,                            
            items: [{
                id: 'notes',
                xtype: 'textarea',
                fieldLabel: 'Notes',                        
                width: 250,
                allowBlank: true
            width: 100,
            items: [{
                style: 'padding-left: 5px;',
                id: 'addNotesButton',
                xtype: 'button',
                text: 'Add Notes',
                handler: addNote

I want to put button at the bottom of the column.
I try this in the id:'addNotesButton':
style: 'padding-left: 5px;padding-top:45px',
It is worked.

But is it the only to do this?

Thanks for your attention.