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
/**
	 * Hook method that gets called when the list of super interface has changed. The method 
	 * validates the super interfaces and returns the status of the validation.
	 * <p>
	 * Subclasses may extend this method to perform their own validation.
	 * </p>
	 * 
	 * @return the status of the validation
	 */
	protected IStatus superInterfacesChanged() {
		StatusInfo status= new StatusInfo();
		
		IPackageFragmentRoot root= getPackageFragmentRoot();
		fSuperInterfacesDialogField.enableButton(0, root != null);
						
		if (root != null) {
			List elements= fSuperInterfacesDialogField.getElements();
			int nElements= elements.size();
			for (int i= 0; i < nElements; i++) {
				String intfname= (String)elements.get(i);
				try {
					IType type= findType(root.getJavaProject(), intfname);
					if (type == null) {
						status.setWarning(NewWizardMessages.getFormattedString("NewTypeWizardPage.warning.InterfaceNotExists", intfname)); 
						return status;
					} else {
						if (type.isClass()) {
							status.setWarning(NewWizardMessages.getFormattedString("NewTypeWizardPage.warning.InterfaceIsNotInterface", intfname));