This patch just makes some simple manipulations with java bytecode using
javassist library. Procedure "processJar" unpacks PictureViewer.jar, finds "g.class" file, sends it to "ProcessClass" procedure and pack jar again. "ProcessClass" adds to end of method "g.stop" call of function "m()" (this function triggers fullscreen mode) and adds to method "g.stop" disabling of fullscreen flag - variable "D".