ScreenShots stored in wp-admin folder

this plugin is great, it’s just really sad screenshots are stored in the wp-admin folder. this causes big problems.
The right thing to do would be to store them in the wp-content/uploads/ folder. Your plugin should create a folder for himself (wp-content/uploads/user-screenshot/).
I actually modified your plugin in order to do that and I highly advice you to change this ASAP and I noticed a “@todo Revisit file handling.” in your AjaxHandler code.
regards