Hey Nhiet
To be honest with you, I have absolutely no idea. What I can see is that the player image has been distorted both horizontally and vertically which means that button positions no longer align with the recesses. These are placed by pixel location and clearly they are where I would expect them to be but the background image is over-stretched.
I tested the skin on various screen resolutions and did not find any problems. I personally use them on a 28inch monitor and they perform faultlessly. There have been literally thousands of downloads of my skins and I've had nobody else report this problem.
Quite why the main library panels have not been populated with data is also unusual.
I notice that you have the image in full screen display, does anything change to correct the image if you alter the window size?
I'm hoping that one of the more 'techy' people on here may have a better idea than me and if anyone reading this knows what's happened, both Nhiet and I would be grateful of your input.
In the meantime...let's check some basics....
-If you install another skin and select that, does it have the same problem? (try installing it by simply copying the skins .xmlc file to your skin directory and select if from the skin list (Menu/View/Skins...) if it doesn't have a problem, try copying the BeatBar skin's .xmlc file in the same way and see if that too is fine.
-Have you tried using a different monitor such as laptop screen or hdmi to TV screen, etc. If that works it would point very much at being WQHD monitor related.