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
return null;
	}
	
	/**
	 * Sets the package fragment to the given value. The method updates the model 
	 * and the text of the control.
	 * 
	 * @param pack the package fragment to be set
	 * @param canBeModified if <code>true</code> the package fragment is
	 * editable; otherwise it is read-only.
	 */
	public void setPackageFragment(IPackageFragment pack, boolean canBeModified) {
		fCurrPackage= pack;
		fCanModifyPackage= canBeModified;
		String str= (pack == null) ? "" : pack.getElementName(); 
		fPackageDialogField.setText(str);
		updateEnableState();
	}	
	/**
	 * Returns the enclosing type corresponding to the current input.
	 * 
	 * @return the enclosing type or <code>null</code> if the enclosing type is 
	 * not selected or the input could not be resolved
	 */
	public IType getEnclosingType() {
		if (isEnclosingTypeSelected()) {
			return fCurrEnclosingType;
		}
		return null;
	}