Bug 42587 Left over from content assist
M3 - set preference that content assist should overwrite - open content assist on some word so that the rest of the word is indicated to be overwritten - transfer focus to the content assist widget using TAB - Esc -> overwrite indication is still there
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/text/link/contentassist/CompletionProposalPopup2.java
long fCounter= fInvocationCounter;
			public void run() {
				
				if (fCounter != fInvocationCounter) return;
				
				int offset= fViewer.getSelectedRange().x;
				ICompletionProposal[] proposals= null;
				try  {
					if (offset > -1) {
						DocumentEvent event= TextUtilities.mergeProcessedDocumentEvents(fDocumentEvents);
						proposals= computeFilteredProposals(offset, event);
					}
				} catch (BadLocationException x)  {
				} finally  {
					fDocumentEvents.clear();
				}
				fFilterOffset= offset;
				
				if (proposals != null && proposals.length > 0)
					setProposals(proposals);
				else
					hide();
			}
		});
	}
	
	/**
	 * Computes the subset of already computed propsals that are still valid for
	 * the given offset.
	 *