FLEX SDK ContainerController updateGraphics Error #1009

error stack：

TypeError: Error #1009: Cannot access a property or method of a null object reference.
    at flashx.textLayout.container::ContainerController/http://ns.adobe.com/textLayout/internal/2008::updateGraphics()[C:\Vellum\branches\v2\2.0\dev\output\openSource\textLayout\src\flashx\textLayout\container\ContainerController.as:3182]
    at flashx.textLayout.container::ContainerController/http://ns.adobe.com/textLayout/internal/2008::updateCompositionShapes()[C:\Vellum\branches\v2\2.0\dev\output\openSource\textLayout\src\flashx\textLayout\container\ContainerController.as:3080]
    at flashx.textLayout.compose::StandardFlowComposer/updateCompositionShapes()[C:\Vellum\branches\v2\2.0\dev\output\openSource\textLayout\src\flashx\textLayout\compose\StandardFlowComposer.as:616]
    at flashx.textLayout.compose::StandardFlowComposer/updateToController()[C:\Vellum\branches\v2\2.0\dev\output\openSource\textLayout\src\flashx\textLayout\compose\StandardFlowComposer.as:559]
    at flashx.textLayout.container::ContainerController/updateForScroll()[C:\Vellum\branches\v2\2.0\dev\output\openSource\textLayout\src\flashx\textLayout\container\ContainerController.as:1119]
    at flashx.textLayout.container::ContainerController/set verticalScrollPosition()[C:\Vellum\branches\v2\2.0\dev\output\openSource\textLayout\src\flashx\textLayout\container\ContainerController.as:985]
    at flashx.textLayout.container::TextContainerManager/set verticalScrollPosition()[C:\Vellum\branches\v2\2.0\dev\output\openSource\textLayout\src\flashx\textLayout\container\TextContainerManager.as:850]
    at spark.components::RichEditableText/commitProperties()[E:\dev\hero_private\frameworks\projects\spark\src\spark\components\RichEditableText.as:2637]
    at mx.core::UIComponent/validateProperties()[E:\dev\hero_private\frameworks\projects\framework\src\mx\core\UIComponent.as:8209]
    at mx.managers::LayoutManager/validateProperties()[E:\dev\hero_private\frameworks\projects\framework\src\mx\managers\LayoutManager.as:597]
    at mx.managers::LayoutManager/doPhasedInstantiation()[E:\dev\hero_private\frameworks\projects\framework\src\mx\managers\LayoutManager.as:813]
    at mx.managers::LayoutManager/doPhasedInstantiationCallback()[E:\dev\hero_private\frameworks\projects\framework\src\mx\managers\LayoutManager.as:1180]

see：http://forums.adobe.com/thread/851572

http://forums.adobe.com/message/3674136＃3674136

这个问题出现在sdk [4.5.0-20967]、[4.5.1-21328]、[4.6.0-22920]上，在此之间这个类没有改动过。在4.5.0-17689这个类使用的是updateFloats方法而不是updateGraphics。

这个错误是基于TLF 2的版本，根据开发论坛所说，这个问题在TLF2.1修复，地址在http://sourceforge.net/projects/tlf.adobe/files ，这个文件不会包含在sdk中，并且也不会提供该SWZ的RSL缓存服务。如果不是非要使用这个版本，官方推荐是使用TLF3.0。

bug：http://bugs.adobe.com/jira/browse/SDK-29654

在http://sourceforge.net/projects/tlf.adobe/files/3.0/current/textLayout_build.zip/download 下载 textLayout_build.zip 解压 libs/textLayout.swc替换掉sdk目录下frameworks/libs/textLayout.swc文件。不过这个貌似是3.0的