Programatically selected FxRadioButton remains selected even after selecting a different FxRadioButton

Steps to reproduce:
1. Compile & run:
<?xml version="1.0" encoding="utf-8"?>
<FxApplication
xmlns="http://ns.adobe.com/mxml/2009" xmlns:local="*"
backgroundColor="0xFFFFFF" >
<layout><VerticalLayout/></layout>

<Declarations>
<FxRadioButtonGroup id="srg"/>
</Declarations>

<VGroup>
<FxRadioButton id="s1" label="Spark 1" />
<FxRadioButton id="s2" label="Spark 2"/>
<FxRadioButton id="s3" label="Spark 3"/>
<FxRadioButton id="s4" label="Spark 4"/>
<FxRadioButton id="s5" label="Spark 5"/>
</VGroup>

<FxButton click="s2.selected=true" label="Select second radiobutton"/>
<FxButton click="s4.selected=true" label="Select fourth radiobutton"/>

</FxApplication>
2. Click on the first button
3. Click on the second button

Actual Results:
Notice both RadioButtons are still selected.

Expected Results:
Only one should be selected. Clicking via mouse does not unselect either RadioButton.

Workaround (if any):
Instead of this:
<FxButton click="s2.selected=true" label="Select second radiobutton"/>

Use this:
<FxButton click="srg.selection=s2" label="Select second radiobutton"/>