Flex 4:The default property contents must be contiguous

In Flash Builder 4, when tried to create a MXML component and instantiate it in the main MXML application, I found that the "Outline" explorer is not displaying the correct tree view anymore, instead it displayed excalmatory marks for each of the components' icon:

And when I switched to the design view in the MXML editor, it failed to render the preview and showed an error message "The default property contents must be contiguous":

However, when I compiled and run the application, everything looked OK. I think this was just an error for the Flash Builder 4 failing to parse and render the outline and preview. The code which was generating such error looks like this:

Code - MXML Plain Text

 

<?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"
               xmlns:components="components.*">
    <fx:Declarations>
        <!-- Place non-visual elements (e.g., services, value objects) here -->
    </fx:Declarations>

    <s:layout>
        <s:VerticalLayout horizontalAlign="center" paddingTop="20"/>
    </s:layout>

    <!-- shorthand MXML bindings -->
    <s:TextInput id="sourceText" text="some value"/>
    <s:Label text="{sourceText.text}"/>

    <!-- two-way bindings -->
    <s:TextInput id="input1" text="@{input2.text}"/>
    <s:TextInput id="input2"/>


    <!-- Using <fx:Binding> -->
    <s:TextInput id="sourceText2" text="some value 2"/>
    <s:Label id="destinationText"/>
    <fx:Binding source="sourceText2.text" destination="destinationText.text"/>

    <!-- Instantiate a MXML component -->
    <components:MyComponent id="comp1"/>
</s:Application>

As the error message said, the visual componets (default property contents) must  be contiguous. So I tried to move the "fx:Binding" tag to just behind the "fx:Declaration" tag, then the error went away.

Code - XML/HTML Plain Text

 

<?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"
               xmlns:components="components.*">
    <fx:Declarations>
        <!-- Place non-visual elements (e.g., services, value objects) here -->
    </fx:Declarations>
    <fx:Binding source="sourceText2.text" destination="destinationText.text"/>

    <s:layout>
        <s:VerticalLayout horizontalAlign="center" paddingTop="20"/>
    </s:layout>

    <!-- shorthand MXML bindings -->
    <s:TextInput id="sourceText" text="some value"/>
    <s:Label text="{sourceText.text}"/>

    <!-- two-way bindings -->
    <s:TextInput id="input1" text="@{input2.text}"/>
    <s:TextInput id="input2"/>

    <!-- Using <fx:Binding> -->
    <s:TextInput id="sourceText2" text="some value 2"/>
    <s:Label id="destinationText"/>

    <!-- Instantiate a MXML component -->
    <components:MyComponent id="comp1"/>
</s:Application>

Note that the "s:layout" from the spark library is also a non-visual component, so it can't be placed between any of the visual components neither, otherwise the same error would occur.

 

from:http://www.inluck.net/Blog/Flash-Builder-4-error-The-default-property-contents-must-be-contiguous