First up, great plugin and many thanks for your continued support with it!
You have function in the plugin: https_cleanup
And you filter the URL only in the admin screen. Would it make more sense to add this filter by default to the loading on all images on the widgets? Currently this is not the case. So I simply added the code:
add_filter( 'image_widget_image_url', array( $this, 'https_cleanup' ) );
after line 36 in your main class. I'd love for this to be either an option to set, or just default in the core code.
Is this do-able?