Full Customizer Support
WordPress Customizer first appeared in WordPress 3.4 and in the meantime it was expanded with more and more features including the support for manipulating sidebars and widgets.
Customizer allows adding of widgets in sidebars and modifying them with live preview on the same screen. All widgets in GD Clever Widgets Pro support fully customizer and live preview and all options will work as you expect them to.
Any new features WordPress adds to customizer will be supported by this plugin when available.