Bug 22380 "No Source" class file editor does not fetch keyboard focus
Build N20020813 Test Case: 1. From the package explorer open a class from a JAR without attached source 2. Activate the editor 3. Select something in another view (note: selection is blue) 4. Activate the class file editor by clicking on the tab ==> selection in other view remains blue but should be gray. Suggest to set the keyboard focus to the "Attach Source..." button
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/javaeditor/ClassFileEditor.java
IFile file= ((IFileEditorInput) input).getFile();
			IClassFileEditorInput classFileInput= new ExternalClassFileEditorInput(file);
			if (classFileInput.getClassFile() != null)
				input= classFileInput;
		}
		
		return input;
	}
	
	/*
	 * @see AbstractTextEditor#doSetInput(IEditorInput)
	 */
	protected void doSetInput(IEditorInput input) throws CoreException {
		input= transformEditorInput(input);
		if (!(input instanceof IClassFileEditorInput))
			throw new CoreException(new JavaUIStatus(IJavaModelStatusConstants.INVALID_RESOURCE_TYPE, JavaEditorMessages.getString("ClassFileEditor.error.invalid_input_message"))); 
		JavaModelException e= probeInputForSource(input);
		if (e != null) {
			IClassFileEditorInput classFileEditorInput= (IClassFileEditorInput) input;
			IClassFile file= classFileEditorInput.getClassFile();
			if (!file.getJavaProject().isOnClasspath(file)) {
				throw new CoreException(new JavaUIStatus(IJavaModelStatusConstants.INVALID_RESOURCE, JavaEditorMessages.getString("ClassFileEditor.error.classfile_not_on_classpath"))); 
			} else {
				throw e;
			}
		}
		IDocumentProvider documentProvider= getDocumentProvider();
		if (documentProvider instanceof ClassFileDocumentProvider)
			((ClassFileDocumentProvider) documentProvider).removeInputChangeListener(this);
		super.doSetInput(input);