lib/form.js
function(context) {
      context.icon = 'loading';
      context.disabled = true;
      if (this.props.loadingMessage) {
        context.children = this.props.loadingMessage;
      }
    }
function(context) {
      context.icon = 'loading';
      context.disabled = true;
      if (this.props.loadingMessage) {
        context.children = this.props.loadingMessage;
      }
    }
apply a loading state to a button