public void removeVerifyKeyListener(VerifyKeyListener verifyKeyListener) {
if (fContentAssistSubjectControl != null) {
fContentAssistSubjectControl.removeVerifyKeyListener(verifyKeyListener);
} else if (fViewer instanceof ITextViewerExtension) {
ITextViewerExtension extension= (ITextViewerExtension) fViewer;
extension.removeVerifyKeyListener(verifyKeyListener);
} else {
StyledText textWidget= fViewer.getTextWidget();
if (Helper.okToUse(textWidget))
textWidget.removeVerifyKeyListener(verifyKeyListener);
}