Refresh that ArrayCollection

So I have this ArrayCollection, which looks basically like this:

 [Bindable]
 public var d1:ArrayCollection = new ArrayCollection(
 [
    { label: 'first', code: 'A', num: 4 },
    { label: 'sec',   code: 'B', num: 7 },
    { label: 'tria',  code: 'C', num: 9 }
 ]
 );

It's the dataProvider for a DataGrid, like this:

<mx:DataGrid id="dg1" 
    dataProvider="{d1}" 
    dragEnabled="true"
    dragDrop="handleDragDrop(event)"
    dropEnabled="true" 
    x="320" y="126">
 <mx:columns>
 <mx:DataGridColumn headerText="Column 1" dataField="label"/>
 <mx:DataGridColumn headerText="Column 2" dataField="code"/>
 <mx:DataGridColumn headerText="Column 3" dataField="num"/>
 </mx:columns>
</mx:DataGrid>

And then, I've got a horizontal slider that sets a value in the ArrayCollection, like this:

 <mx:HSlider id="hslider" x="10" y="320" width="302" 
            minimum="1" maximum="10" snapInterval="1" 
            change="d1.getItemAt(0).num = this.hslider.value" 
            labels="{[1,2,3,4,5,6,7,8,9,10]}" />

So I can slide the slider, and the "num" attribute of the first element in d1 changes, but the display list in the datagrid doesn't change. And so I learned (or perhaps re-learned) a lesson today:

Whenever you change data in a data provider, also call refresh() on it.

Not only does this re-run filters and sorts, it also refreshes the display. So when a single value changes, calling refresh() will update display lists that are bound to the array.

So, the slider's change property should look like this:

   change="d1.getItemAt(0).num = this.hslider.value; d1.refresh()"

I'm actually using these widgets in a web application I'm slowly working on, which has a web of components that interact with each other. It's wargame rules for starship combat for a pencil-and-paper game called Traveller:

http://eaglestone.pocketempires.com/rules/t5/starships/Shipyard.html