the org.eclipse.swt.swtexception:Invalid Thread access when choose a wsdl file in the import wsdl wizard

Open a bpel file, click on the blank of the editor.
In the properties view, choose the Import tab
Click the 'Import an XSD' button, a wizard opens
On the resource wizard page, you can get all the wsdl and xsd file in the eclipse workspace. But when you choose an wsdl file from other projects, a error occured:
org.eclipse.swt.swtexception:Invalid Thread access.