[Engine] Sound playback problem solved
[Engine] Fixed reporting of changed screen size
[Engine-Slick2D] Fixed blending at transparent parts of the scene
[Engine-Slick2D] Fixed graphics blending
[Engine-Slick2D] Fixed drag forwarding

Dragging works now in the Nifty-GUI
[Engine-Slick2D] Fixed handling of transparent scene parts
[Engine] Added support for scene events that got not handled