The button should be added at the top right corner of the formatted code snippet.

It should use JavaScript only and not an applet so that content generated from RadEditor can be re-used in other pages.

Ideally, it will copy plain text with preserved indentation to the clipboard.

Whether the button will be added should be controlled via a checkbox in the Format Code Block dialog. Leave your comment whether you want it checked by default (which can be considered a breaking change).