Disable screenshot

On my website I have a plugin installed that disables the right mouse button so that no one can download the photos from my galleries.

Even so I my find photos, stolen, in forums and published, of course, without my authorization. Imagine through screenshots.

Is it possible to disable, like the right button, the screenshot function? Is there a plugin that gets it? … or at least places a watermark on the stolen image.

Thanks in advance

The page I need help with: [log in to see the link]