Enabling Custom CSS Classes for GravityView widgets

If you want to have a Custom CSS Class field in your GravityView Widget settings, add the following code:

/**
 * Enable custom class for GravityView widgets. Requires GravityView 1.5.4 or higher.
 * 
 * @param boolean False by default. Return true if you want to enable it.
 * @param GravityView_Widget Current instance of GravityView_Widget
 */
add_filter('gravityview/widget/enable_custom_class', '__return_true' );