message: Format ListBox header functions as multi-line
  In preparing for making the class a template, member methods will need
  to be moved to the header. That means lots of multi-line functions in
  the header. Ideally all functions should use a consistent formatting
  style.
diff: @@ -60,7 +60,10 @@ public:
  ~ListBox() override;
  bool isEmpty() const;
  - std::size_t count() const { return mItems.size(); }
  +
  + std::size_t count() const {
  + return mItems.size();
  + }
  template <typename... Args>
  void add(Args&&... args) {
  @@ -71,10 +74,21 @@ public:
  void clear();
  bool isItemSelected() const;
  +
  const ListBoxItem& selected() const;
  - std::size_t selectedIndex() const { return mSelectedIndex; }
  - void setSelected(std::size_t index) { mSelectedIndex = index; mSelectionChanged(); }
  - void clearSelected() { mSelectedIndex = constants::NO_SELECTION; }
  +
  + std::size_t selectedIndex() const {
  + return mSelectedIndex;
  + }
  +
  + void setSelected(std::size_t index) {
  + mSelectedIndex = index;
  + mSelectionChanged();
  + }
  +
  + void clearSelected() {
  + mSelectedIndex = constants::NO_SELECTION;
  + }
  template <typename UnaryPredicate>
  void selectIf(UnaryPredicate predicate) {
  @@ -86,13 +100,19 @@ public:
  }
  }
  - std::size_t currentHighlight() const { return mHighlightIndex; }
  + std::size_t currentHighlight() const {
  + return mHighlightIndex;
  + }
  - unsigned int lineHeight() const { return mContext.itemHeight(); }
  + unsigned int lineHeight() const {
  + return mContext.itemHeight();
  + }
  void update() override;
  - SelectionChangedCallback& selectionChanged() { return mSelectionChanged; }
  + SelectionChangedCallback& selectionChanged() {
  + return mSelectionChanged;
  + }
  protected:
  virtual void onMouseDown(NAS2D::EventHandler::MouseButton button, int x, int y);
  