// Invalidate ==> remove applied text presentation
if (!redrawAll && viewer instanceof ITextViewerExtension2)
((ITextViewerExtension2) viewer).invalidateTextPresentation(offset, length);
else
viewer.invalidateTextPresentation();
// Remove underline
if (viewer instanceof ITextViewerExtension5) {
ITextViewerExtension5 extension= (ITextViewerExtension5) viewer;
offset= extension.modelOffset2WidgetOffset(offset);