Excel-like behaviour of Grids in Ext JS - extjs

Question

I'm trying to figure out a way to have an Excel-like behavior with the Grids on Ext JS.
Here is the sample grid I am working with. So far we can already naviguate through the cells with the arrows but only in edit mode.
However what I am trying to reach is the naviguation with the arrows, TAB and Enter keys outside of the edit mode, just like excel.
I tried to integrate this piece of code which overrides the Editor class, hoping that it would change the behavior of the cells but it doesn't change a thing.
I believe this is the most important part that overrides the Editor class and tries to include the keys input :
Ext.override(Ext.Editor, {
startEdit: function (el, value) {
var me = this,
field = me.field;
me.completeEdit();
me.boundEl = Ext.get(el);
value = Ext.isDefined(value) ? value : me.boundEl.dom.innerHTML;
if (!me.rendered) {
me.render(me.parentEl || document.body);
}
if (me.fireEvent('beforestartedit', me, me.boundEl, value) !== false) {
me.startValue = value;
me.show();
field.reset();
if (deleteGridCellValue) {
field.setValue('');
me.editing = true;
me.completeEdit();
deleteGridCellValue = false; // reset global variable
}
else {
if (newGridCellValue == '') {
// default behaviour of Ext.Editor (see source if needed)
field.setValue(value);
}
else {
// custom behaviour to handle an alphanumeric key press from non-edit mode
field.setRawValue(newGridCellValue);
newGridCellValue = ''; // reset global variable
if (field instanceof Ext.form.field.ComboBox) {
// force the combo box's filtered dropdown list to be displayed (some browsers need this)
field.doQueryTask.delay(field.queryDelay);
}
}
me.realign(true);
field.focus(false, 10);
if (field.autoSize) {
field.autoSize();
}
me.editing = true;
}
}
}
});
This is the first time that I am working on a project that is outside of Comp-Sci classes so any help would be very much appreciated. Thanks !