Bug 96917 [implementation] If two editors use the 2.x-compatible API, one or both doesn't work
At least one problem is that 3.0 installs partitioners for every editor that might possibly edit a file, but each editor expects its own partitioner to be installed. Leading to the famous white screen with blue line.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/javaeditor/DocumentAdapter.java
buf.append(String.valueOf((int) curr.charAt(k)));
					}
					JavaPlugin.log(new Exception(buf.toString()));
				}
			} catch (BadLocationException e) {
				JavaPlugin.log(e);
			}
		}
	}
	/*
	 * @see IDocumentListener#documentAboutToBeChanged(DocumentEvent)
	 */
	public void documentAboutToBeChanged(DocumentEvent event) {
		
	}
	/*
	 * @see IDocumentListener#documentChanged(DocumentEvent)
	 */
	public void documentChanged(DocumentEvent event) {
		fireBufferChanged(new BufferChangedEvent(this, event.getOffset(), event.getLength(), event.getText()));
	}
	private void fireBufferChanged(BufferChangedEvent event) {
		if (fBufferListeners != null && fBufferListeners.size() > 0) {
			Iterator e= new ArrayList(fBufferListeners).iterator();
			while (e.hasNext())
				((IBufferChangedListener) e.next()).bufferChanged(event);
		}
	}
}