private @Nullable Font editFontSize(String key, Font font) {
        String newValue = Messages.showInputDialog(getRootPane(),
                                                   IdeBundle.message("label.enter.new.font.size.for.0", key),
                                                   IdeBundle.message("dialog.title.font.size.editor"), null,
                                                   Integer.toString(font.getSize()),
                                                   new InputValidator() {
                                                     @Override
                                                     public boolean checkInput(String inputString) {
                                                       return parseFontSize(font, inputString) != null;
                                                     }

                                                     @Override
                                                     public boolean canClose(String inputString) {
                                                       return checkInput(inputString);
                                                     }
                                                   });

        return newValue != null ? parseFontSize(font, newValue) : null;
      }
private @Nullable Font editFontSize(String key, Font font)