Sanitize AROUND shortcode

Try to use this instead:

editor.focus();
var selected_text = editor.selection.getContent();
shortcode="[checklist-box title="" + e.data.title + '"]' + selected_text + '[/checklist-box]';
editor.selection.setContent(shortcode);
editor.setContent(editor.getContent());

Basically, I’m first forcing editor focus and then use setContent instead to change the content. In my tests there were still some glitches on the editor but the source was ok, so I just copy all content and set it again to refresh the editor.