Bug 52064 Content assist in "New Class" Dialog shows interfaces
Content Assist is available for the superclass in M7. However it also lists interfaces. If an interface is selected, the generated class "extends" it instead of "implementing" it.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/ui/wizards/NewTypeWizardPage.java
/**
	 * @deprecated Use createInheritedMethods(IType,boolean,boolean,IImportsManager,IProgressMonitor)
	 */
	protected IMethod[] createInheritedMethods(IType type, boolean doConstructors, boolean doUnimplementedMethods, IImportsStructure imports, IProgressMonitor monitor) throws CoreException {
		return createInheritedMethods(type, doConstructors, doUnimplementedMethods, new ImportsManager(imports), monitor);
	}
	
	
	/**
	 * Returns the runnable that creates the type using the current settings.
	 * The returned runnable must be executed in the UI thread.
	 * 
	 * @return the runnable to create the new type
	 */		
	public IRunnableWithProgress getRunnable() {				
		return new IRunnableWithProgress() {
			public void run(IProgressMonitor monitor) throws InvocationTargetException, InterruptedException {
				try {
					if (monitor == null) {
						monitor= new NullProgressMonitor();
					}
					createType(monitor);
				} catch (CoreException e) {
					throw new InvocationTargetException(e);
				} 				
			}
		};
	}	
}