Description Resource Path Location Type The swc
‘E:\DEV\Flash\Flex\SDK\4.14.1\frameworks\libs\advancedgrids.swc’ has
style defaults and is in the library-path, which means dependencies
will be linked in without the styles. This can cause applications,
which use the output swc, to have missing skins. The swc should be
put in the external-library-path.

SharedSledi Unknown Flex Problem
The swc ‘E:\DEV\Flash\Flex\SDK\4.14.1\frameworks\libs\charts.swc’ has
style defaults and is in the library-path, which means dependencies
will be linked in without the styles. This can cause applications,
which use the output swc, to have missing skins. The swc should be
put in the external-library-path.

SharedSledi Unknown Flex Problem
The swc ‘E:\DEV\Flash\Flex\SDK\4.14.1\frameworks\libs\framework.swc’
has style defaults and is in the library-path, which means
dependencies will be linked in without the styles. This can cause
applications, which use the output swc, to have missing skins. The
swc should be put in the
external-library-path.

SharedSledi Unknown Flex Problem The swc
‘E:\DEV\Flash\Flex\SDK\4.14.1\frameworks\libs\mx\mx.swc’ has style
defaults and is in the library-path, which means dependencies will be
linked in without the styles. This can cause applications, which use
the output swc, to have missing skins. The swc should be put in the
external-library-path.

SharedSledi Unknown Flex Problem The swc
‘E:\DEV\Flash\Flex\SDK\4.14.1\frameworks\libs\spark.swc’ has style
defaults and is in the library-path, which means dependencies will be
linked in without the styles. This can cause applications, which use
the output swc, to have missing skins. The swc should be put in the
external-library-path. SharedSledi Unknown Flex Problem

>如何使用缺少的默认外观解决此问题？

最佳答案 正如错误消息所示：“swc应该放在外部库路径中”

查看此官方指南：Use Flex library projects,具体阅读本section link.引用：

1)将SWC文件添加到库路径

Add a SWC file to the library path

1. With a project selected in the Package Explorer, select Project > Properties > Flex Build Path.

2. Click the Library Path tab.

3. Select any of these options to add SWC files:

   • Add Project Adds a Flex library project.

   • Add SWC Folder Lets you add a folder that contains SWC files.

   • Add SWC Adds a compiled SWC file.

   • Add Flex SDK Lets you add other Flex SDKs. If your project already has a Flex SDK in its library path, this button is disabled.
     If you remove the existing Flex SDK from your library path, the button
     is enabled. When you click this button, a Flex SDK node is added, but
     you are not prompted which one is added. To control which Flex SDK to
     use, select Project > Properties > Flex Compiler.

4. Enter or browse to and select the location of the SWC file, project, or folder. Click OK. The SWC file, library project, or folder
   is added to the library path.

2)将SWC设置为外部库…

Set the SWC file as an external library file

1. With a project selected in the Package Explorer, select Project > Properties > Flex Build Path.

2. Select the Library Path tab, and then select and expand the SWC file entry to display the SWC options.

3. Double-click the Link Type option. The Library Path Items Options dialog box appears

4. Select the External option, and click OK.

This procedure is the equivalent of using the external-library-path
compiler option.

PS：如果您愿意编辑Flash Builder的XML文件,那么Answer可能会为您提供一些线索.