Bug 91266 [refactor/code completion] change method signature, code completion not useable
We can with CTRL-SPACE initalize code completion in the type selection of the change method signature. But if we then press enter to select the right type we just pointed out with code completion. The enter is consumed by the table below and the selected value in the code completion popup is ignored. So yes you can see what values there are but as far as i know you can't select them with the keyboard (mouse is possible)
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/dialogs/TableTextCellEditor.java
public interface IActivationListener {
		public void activate();
	}
	
	private final TableViewer fTableViewer;
	private final int fColumn;
	private final String fProperty;
	/**
	 * The editor's value on activation. This value is reset to the
	 * cell when the editor is left via ESC key.
	 */
	Object fOriginalValue;
	SubjectControlContentAssistant fContentAssistant;
	private IActivationListener fActivationListener;
	
    protected Text text;
    private boolean isSelection = false;
    private boolean isDeleteable = false;
    private boolean isSelectable = false;
    private static final int defaultStyle = SWT.SINGLE;
	private ModifyListener fModifyListener;
	
	public TableTextCellEditor(TableViewer tableViewer, int column) {
		super(tableViewer.getTable(), defaultStyle);
		fTableViewer= tableViewer;
		fColumn= column;