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/JavaCorrectionAssistant.java
private static Color getColor(IPreferenceStore store, String key, IColorManager manager) {
		RGB rgb= PreferenceConverter.getColor(store, key);
		return manager.getColor(rgb);
	}
	/* (non-Javadoc)
	 * @see org.eclipse.jface.text.contentassist.IContentAssistant#install(org.eclipse.jface.text.ITextViewer)
	 */
	public void install(ITextViewer textViewer) {
		super.install(textViewer);
		fViewer= textViewer;
		fLightBulbUpdater= new QuickAssistLightBulbUpdater(fEditor, textViewer);
		fLightBulbUpdater.install();
	}
	/* (non-Javadoc)
	 * @see org.eclipse.jface.text.contentassist.ContentAssistant#uninstall()
	 */
	public void uninstall() {
		if (fLightBulbUpdater != null) {
			fLightBulbUpdater.uninstall();
			fLightBulbUpdater= null;
		}
		super.uninstall();
	}
	/*
	 * @see org.eclipse.jface.text.quickassist.QuickAssistAssistant#showPossibleQuickAssists()
	 * @since 3.2
	 */
	/**
	 * Show completions at caret position. If current
	 * position does not contain quick fixes look for