Test Grid Store Observation

## Simple test to show setting a new store and query to dgrid

## Simple test to show editor effect on store data

### Dirty Items

The following buttons switch between stores in the left grid above, to test handling of errors on put operations.

Note that clicking Save will NOT emit an error event on the grid, as direct invocations of save are expected to handle the returned promise as they see fit. However, modifying an editor field with autoSave enabled will cause an error event to be emitted, since in this case it is the grid which initiated the operation.

## Simple test to show adding/deleting items

(With an OnDemandList alongside, also observing the changes)

## OnDemandGrid using store with Stateful objects