public void inputChanged(Viewer viewer, Object oldInput, Object newInput) {
if (oldInput != null) {
IDocument document = fDocumentProvider.getDocument(oldInput);
if (document != null) {
try {
document.removePositionCategory(SEGMENTS);
} catch (BadPositionCategoryException e) {
WodclipsePlugin.getDefault().log(e);
}
document.removePositionUpdater(fPositionUpdater);
}