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.tests/ui/org/eclipse/jdt/ui/tests/quickfix/MarkerResolutionTest.java
private static final class TextViewerContext implements IQuickAssistInvocationContext {
		private ITextViewer fTextViewer;
		private int fOffset;
		
		TextViewerContext(ITextViewer textViewer, int offset) {
			fTextViewer= textViewer;
			fOffset= offset;
		}
		/*
		 * @see org.eclipse.jface.text.quickassist.IQuickAssistInvocationContext#getOffset()
		 */
		public int getOffset() {
			return fOffset;
		}
		/*
		 * @see org.eclipse.jface.text.quickassist.IQuickAssistInvocationContext#getLength()
		 */
		public int getLength() {
			return -1;
		}
		/*
		 * @see org.eclipse.jface.text.quickassist.IQuickAssistInvocationContext#getTextViewer()
		 */