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
BusyIndicator.showWhile(styledText.getDisplay(), new Runnable() {
			public void run() {
				
				fInvocationOffset= fViewer.getSelectedRange().x;
				
				fComputedProposals= computeProposals(fInvocationOffset);
				
				int count= (fComputedProposals == null ? 0 : fComputedProposals.length);
				if (count == 0) {
					
					if (!autoActivated)
						styledText.getDisplay().beep();
				
				} else {
					
					if (count == 1 && !autoActivated && fContentAssistant.isAutoInserting())
						
						insertProposal(fComputedProposals[0], (char) 0, 0, fInvocationOffset);
					
					else {
					
						if (fLineDelimiter == null)
							fLineDelimiter= styledText.getLineDelimiter();
						
						createProposalSelector();
						setProposals(fComputedProposals);
						resizeProposalSelector(true);
						displayProposals();
					}
				}