sDrop is a processing library that lets you drag and drop objects such as files, images, bookmarks, or text into your processing sketch. once dropped you can access the information of the object from a DropEvent that has been forwarded to the processing sketch.
unzip and put the extracted sDrop folder into your processing sketches folder. reference and examples are also included in the sDrop folder. You need to restart processing if it is the first time you are adding sDrop to your libraries.
Export to Applet
The security regulations for applets are very high and strict, in order to make sDrop work properly within an applet, you need to make fields and functions which are used by sDrop public in your code.
Reference. Have a look at the javadoc reference here. a copy of the reference is included in the .zip as well.