Is it possible to use WSPBuilder to create a sandboxed solution?

Question

i am trying to build a sandboxed sharepoint solution using WSPBuilder, but gets an exception when activating the feature, that the Resources element in manifest.xml is invalid. The Resources element lists the files contained in a module which is a part of a feature. The solution does not contain any non-sandboxable features, as the same solution created without WSPBuilder can be activated. Has anyone tried to do this, and made it work?

This is the manifest.xml created by wspbuilder (slightly anonymized):

<?xml version="1.0"?>
<!-- Solution created by WSPBuilder. 06.01.2011 15:02:38 * Solution compatibility: SharePoint 2010 -->
<Solution SolutionId="2235f481-04a4-4e9c-8c04-ed71c0b68cdf" Title="Branding Sandboxed" xmlns="http://schemas.microsoft.com/sharepoint/">
  <Assemblies>
    <Assembly Location="BrandingSolution.dll" DeploymentTarget="GlobalAssemblyCache" />
  </Assemblies>
  <FeatureManifests>
    <FeatureManifest Location="Branding\feature.xml" />
  </FeatureManifests>
  <Resources>
    <Resource Location="Branding\abc.master" />
    <Resource Location="Branding\abcscript.js" />
    <Resource Location="Branding\abcstyle.css" />
    <Resource Location="Branding\bg_resourceregion.gif" />
    <Resource Location="Branding\favicon.ico" />
    <Resource Location="Branding\jquery-1.4.2.min.js" />
  </Resources>
</Solution>

The manifest.xml created by VS is as follows (same functionality created with the VS tools):

<?xml version="1.0" encoding="utf-8"?>
<Solution xmlns="http://schemas.microsoft.com/sharepoint/" SolutionId="50e67e9e-2e3f-4034-8a0d-5aa7ce8dc89e" SharePointProductVersion="14.0">
  <Assemblies>
    <Assembly Location="SandboxedBranding.dll" DeploymentTarget="GlobalAssemblyCache" />
  </Assemblies>
  <FeatureManifests>
    <FeatureManifest Location="SandboxedBranding_Branding\Feature.xml" />
  </FeatureManifests>
</Solution>