Bug 43488 [typing] BadPositionCategoryException in LinkedPositionManager
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/text/link/contentassist/ContentAssistant2.java
if (fViewer instanceof ITextViewerExtension) {
				ITextViewerExtension extension= (ITextViewerExtension) fViewer;
				extension.removeVerifyKeyListener(fAutoAssistListener);
			} else {
				StyledText textWidget= fViewer.getTextWidget();
				if (Helper2.okToUse(textWidget))
					textWidget.removeVerifyKeyListener(fAutoAssistListener);
			}
			
			fAutoAssistListener= null;
		}
	}
	
	/**
	 * Sets the delay after which the content assistant is automatically invoked
	 * if the cursor is behind an auto activation character. 
	 *
	 * @param delay the auto activation delay
	 */
	public void setAutoActivationDelay(int delay) {
		fAutoActivationDelay= delay;
	}
	
	/**
	 * Sets the proposal popups' orientation.
	 * The following values may be used:
	 * <ul>
	 *   <li>PROPOSAL_OVERLAY<p>
	 *     proposal popup windows should overlay each other