New events/extension points for dijit.form.FilteringSelect

[rmaccracken]

We use FilteringSelect? widgets connected to data stores in many places. In some cases, the queries invoked by the data stores can take a few seconds. In those cases, we would like to get notified when a query begins and when a query ends. I think one way to do this would be to make _fetchHandle "watch"able.

This will allow us to show some indication to the user that the widget is busy. I was thinking of maybe changing the background color of the drop-down arrow to some shade of red (or just changing the icon itself). Firefox does something similar with the address bar while loading a page.

If you would like to add that as an option to the widget, then great. If not, then exposing the _fetchHandle as a watchable attribute should allow me to do it.

Thanks.

[dylan]

Will consider for 1.12.

[dylan]

Ticket planning... move current 1.13 tickets out to 1.15 to make it easier to move tickets into the 1.13 milestone.