Yup, there is.
That opens up a side window where you can upload your image and then append it in the message from there.
Sometimes it can be a bit buggy and not work when creating a new topic. In that case create the topic with the question and then create an answer with the image. :)
There is a bug when you first create a post under a video the image won't post. You can simply add a reply to the post with the screenshot or edit the post after you create it.
