Bug 76439 Classfile editor: Allow source attachment option for classes in class folders
20041017 When you open a class file for a class folder that has no source attchment you see a message 'No source available...' but no button that brings you to the source attachment page like it is done for JARs. ClassfileEditor line 225 is too restrictive, the test .isArchive() seems to be too much
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/javaeditor/ClassFileEditor.java
* Removed methods isSaveOnClosedNeeded and isDirty.
	 * Added method isEditable.
	 */
	/*
	 * @see org.eclipse.ui.texteditor.AbstractTextEditor#isEditable()
	 */
	public boolean isEditable() {
		return false;
	}
	
	/**
	 * Translates the given editor input into an <code>ExternalClassFileEditorInput</code>
	 * if it is a file editor input representing an external class file.
	 * 
	 * @param input the editor input to be transformed if necessary
	 * @return the transformed editor input
	 */
	protected IEditorInput transformEditorInput(IEditorInput input) {
		
		if (input instanceof IFileEditorInput) {
			IFile file= ((IFileEditorInput) input).getFile();
			IClassFileEditorInput classFileInput= new ExternalClassFileEditorInput(file);
			if (classFileInput.getClassFile() != null)
				input= classFileInput;
		}
		
		return input;
	}
	
	/*