The custom widget does not show up in the DockWidgetContainer

Description

When using ArcWeb Explorer Flex API, the custom widget does not show up in the DockWidgetContainer.

Cause

The DockWidgetContainer requires the ICON widget state to be implemented.

Solution or Workaround

Code:
<widget:DockWidgetContainer>
     <!-- widgets needs ICON state for DockWidgetContainer -->
     <widget:MyThirdWidget id="dockedW"/>
</widget:DockWidgetContainer>

Code:
<widget:IconWidgetView toolTip="DockWidgetContainer use ICON widget state"
	widget="{m_widget}"
	upIcon="@Embed(source='images/customUp.png')"
	downIcon="@Embed(source='images/customDown.png')"
	overIcon="@Embed(source='images/customOver.png')"
	disabledIcon="@Embed(source='images/customDisabled.png')"/>

Code:
<widget:MyDockedWidget
    xmlns:widget="com.esri.aws.awx.widget.*"
    name="Widget #3"
    widgetStates="{[WidgetStates.DEFAULT,WidgetStates.ICON]}"/>