Bug 127655 [api] Must have a way to query quick assist context from source viewer
I20060214-0010 [api] Must have a way to query quick assist context from text viewer. In addition, quick assistant install must specify that besides ITextViewer also ITextViewerExtension7 must be present in order to get the invocation context. ==> assertion failure if this is not met.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/text/correction/PropertiesFileCorrectionProcessor.java
* @see IContentAssistProcessor#computeCompletionProposals(ITextViewer, int)
	 */
	public ICompletionProposal[] computeQuickAssistProposals(IQuickAssistInvocationContext quickAssistContext) {
		ITextViewer viewer= quickAssistContext.getTextViewer();
		int documentOffset= quickAssistContext.getOffset();
		IEditorPart part= fAssistant.getEditor();
		int length= viewer != null ? viewer.getSelectedRange().y : 0;
		AssistContext context= new AssistContext(null, documentOffset, length);
		fgErrorMessage= null;
		ArrayList proposals= new ArrayList();
		IAnnotationModel model= null;
		IEditorInput input= part.getEditorInput();
		if (!(input instanceof IStorageEditorInput))
			return null;
		ITextFileBufferManager manager= FileBuffers.getTextFileBufferManager();
		IPath path= null;
		try {
			path= ((IStorageEditorInput)input).getStorage().getFullPath();
			if (path == null)
				return null;
			manager.connect(path, null);
		} catch (CoreException e) {
			JavaPlugin.log(e.getStatus());
			return null;
		}
		try {
			model= manager.getTextFileBuffer(path).getAnnotationModel();
			if (model != null) {
				processAnnotations(context, model, proposals);
			}