Flex 4 Panel skin has dependency on 'pattern_147.gif' -- Where is this?

I am trying to create a new skin for the spark Panel based on a copy of the existing skin spark.skins.spark.PanelSkin. Inside my skin is the following:

            <s:Rect id="tbFill" left="0" right="0" top="0" bottom="1">
                <s:fill>
              开发者_运维问答      <s:BitmapFill source="@Embed('assets/pattern_147.gif')" fillMode="repeat" />
                </s:fill>
            </s:Rect>

But I am getting a flex compiler error that says it cannot find this. Where can I locate it so I can add it to my project? I don't know if it makes any difference, but I am using Maven/Flexmojos to get my Flex 4.1 SDK SWC files. I am OK with working around the existence of this GIF, but it strikes me as odd that Adobe would create this dependency then not give you the asset.

The title bar fill from sdk 4.1 (build 16076) which is a stable build produces the following code:

<s:Rect id="tbFill" left="0" right="0" top="0" bottom="1">
    <s:fill>
        <s:LinearGradient rotation="90">
            <s:GradientEntry color="0xE2E2E2" />
            <s:GradientEntry color="0xD9D9D9" />
        </s:LinearGradient>
    </s:fill>
</s:Rect>

You're probably using nightly builds of the sdk, which might explain such an oversight.