Does Spark Grid replace MX Grid? - components

Question

I wanted to use the Spark Grid but at the same time I realized there are no Spark equivalents for certain components like the <GridItem>.
So, I mixed both Spark and Halo components in the program but when I ran it, I got the error:
"TypeError: Error #1034: Type Coercion failed: cannot convert spark.components::Grid#239b40a1 to mx.containers.Grid."
The program:
<?xml version="1.0" encoding="utf-8"?>
<s:Application xmlns:fx="http://ns.adobe.com/mxml/2009"
xmlns:s="library://ns.adobe.com/flex/spark"
xmlns:mx="library://ns.adobe.com/flex/mx" minWidth="955" minHeight="600">
<s:Grid>
<mx:GridRow id="row1">
<mx:GridItem>
<s:Label text="Description:" paddingTop="5"/>
</mx:GridItem>
<mx:GridItem>
<s:TextArea id="descTI" width="300" height="50"/>
</mx:GridItem>
</mx:GridRow>
<mx:GridRow id="row2">
<mx:GridItem>
<s:Label text="Name:" paddingTop="5"/>
</mx:GridItem>
<mx:GridItem>
<s:TextInput id="nameTI" width="300"/>
</mx:GridItem>
</mx:GridRow>
<mx:GridRow id="row3">
<mx:GridItem>
<s:Label text="Target:" paddingTop="5"/>
</mx:GridItem>
<mx:GridItem>
<s:TextInput id="targetTI" width="300"/>
</mx:GridItem>
</mx:GridRow>
<mx:GridRow id="row5">
<mx:GridItem>
<s:Label text="Operand:" paddingTop="5" />
</mx:GridItem>
<mx:GridItem>
<mx:DataGrid id="attrDG">
<mx:columns>
<mx:DataGridColumn dataField="variable" width="150"/>
<mx:DataGridColumn dataField="level"
width="150"/>
</mx:columns>
</mx:DataGrid>
</mx:GridItem>
<mx:GridItem paddingLeft="3" colSpan="2">
<mx:DataGrid id="attrDG0">
<mx:columns>
<mx:DataGridColumn dataField="variable" width="150"/>
<mx:DataGridColumn dataField="level"
width="150"/>
</mx:columns>
</mx:DataGrid>
</mx:GridItem>
</mx:GridRow>
</s:Grid>
</s:Application>

Answer 1

The spark.components.Grid is not meant to replace the mx.containers.Grid. Rather, it's immediate use is as a component of the spark.components.DataGrid component, which is meant to render items in a data provider which implements an IList. See the language reference documentation on the Spark Grid for more details.
You should continue to use the mx:Grid. You can even find examples of it being used in the official Using Flex 4.5 reference: MX Grid layout container.
I will offer the observation, however, that you might also want to look at the s:Form container. The manner in which you are laying out the first three rows seems to me more suited to the use case the Form was designed for.
Finally, the s:DataGrid is intended to replace the mx:DataGrid. So you should make sure to use that.