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
switch (e.keyCode) {
	
					case SWT.ARROW_LEFT :
					case SWT.ARROW_RIGHT :
						filterProposals();
						return true;
	
					case SWT.ARROW_UP :
						newSelection -= 1;
						if (newSelection < 0)
							newSelection= fProposalTable.getItemCount() - 1;
						break;
	
					case SWT.ARROW_DOWN :
						newSelection += 1;
						if (newSelection > fProposalTable.getItemCount() - 1)
							newSelection= 0;
						break;
						
					case SWT.PAGE_DOWN :
						newSelection += visibleRows;
						if (newSelection >= fProposalTable.getItemCount())
							newSelection= fProposalTable.getItemCount() - 1;
						break;
						
					case SWT.PAGE_UP :
						newSelection -= visibleRows;
						if (newSelection < 0)
							newSelection= 0;
						break;