Bug 43488 [typing] BadPositionCategoryException in LinkedPositionManager
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/text/link/contentassist/ContentAssistant2.java
*/
	private void uninstallKeyListener() {
		if (fKeyListenerHooked) {
			StyledText text= fViewer.getTextWidget();
			if (Helper2.okToUse(text)) {
				
				if (fViewer instanceof ITextViewerExtension) {
					ITextViewerExtension e= (ITextViewerExtension) fViewer;
					e.removeVerifyKeyListener(fInternalListener);
				} else {
					text.removeVerifyKeyListener(fInternalListener);
				}
				
				fKeyListenerHooked= false;
			}
		}
	}
	
	/**
	 * Returns the number of listeners.
	 *
	 * @return the number of listeners
	 * @since 2.0
	 */
	private int getNumberOfListeners() {
		int count= 0;
		for (int i= 0; i <= CONTEXT_INFO_POPUP; i++) {
			if (fListeners[i] != null)
				++ count;
		}