offer access to the grid instance itself from any event

[StephanWald]

When having multiple grids on a form all allowing selection events, you cannot tell from the event payload which grid fired an event. In some cases it might be desirable to have a central event handler and that the event payload tells which grid instance triggered the event.

I suggest an additional member field to each event payload object containing the #this! pointer to the grid instance itself.

BBj event payloads always return a handle to the control instance that was firing the event, so it would be consistent also in regard to the expectations of a BBj developer.