When an image is being dragged using <drag_info>, the percentage of the image that is allowed off the edge of the screen before <drag_drop> is executed.
Note that if the value in <edge_detection> is 100, the entire image will disappear off the edge of the screen and will not be able to be dragged back.
The value in <edge_detection> can be negative. This will cause a buffer to form within the edge of the image where the image cannot be dragged. If the value is -100, the buffer will be the size of the image itself.
Child of: <drag_info>
Parent of: Nothing
Example:
<edge_detection>50</edge_detection>