Bug 131000 [EFS] Drag and Drop of Folder with Spaces produces two folders in Navigator View (and other views that deal with resources)
If you grab a folder on the file system that has spaces in the name and drag it into a project in the navigator view, the folder is copied twice, once with escaped spaces (%20) and once without any escaped spaces. The folder with escaped spaces is the one with the content, the other folder has no content. This is a fairly serious bug for us because we use the CopyFilesAndFoldersOperation to do our own manipulation like this and the bug is in that class.
bundles/org.eclipse.ui.ide/src/org/eclipse/ui/wizards/datatransfer/FileStoreStructureProvider.java
/**
	 * Holds a singleton instance of this class.
	 */
	public final static FileStoreStructureProvider INSTANCE = new FileStoreStructureProvider();
	/*
	 * (non-Javadoc)