how to make bsplayer keep aspect ratio in full screen?

[LoWang]

Hello I use BSplayer free. I have a 16:10 display and I want to watch a 856*480 video. I usually run it and switch to full screen by double clicking, but I noticed that the image is stretched vertically! WTH? I have to press M key twice - it sets the original aspect ratio but the image is now cropped (right and left side off the screen) and on the second keypress it fits the screen with the right aspect ratio which is what I want. But whenever I double click to go back to window mode and then go back to fullscreen it is stretched again :-\ Even when the option video/keep aspect ratio is checked! It has no effect. I did not find any settings to prevent this strange behavior. Thanks for an advice.