Skin for the whole screen
 

I am new to BS player, but it seems that there is no such skin or feature in the player that allows to maximize the player to the whole screen without making video full-sized... It is really incinvinient to watch video when with my lateral sight I see pieces of windows and backgroud outside the video (video size is smaller than the screen size). Can someone advise me if there is such a skin that can be maximized for the whole screen leaving the area around video just black for example? (or maybe there is such feature, I didn't find...)
Thanks.

i'm not sure if this is what you want but...have you tried selecting the 'don't resize video in fullscreen' option under the 'general' tab of the 'video' section of the preferences window.

Well, actually, yes. That's the result that I wanted to get (although, it is not the way I wanted to get such result). But now, after I tried this I am faced with another problem: when I want it to be really full-screen (resized to full screen) I will have to go to Preferences and there uncheck that check. So it is still inconvinient. I think the ideal would be to make the player same as Windows Media Player where the area around the video is black but it is done not by not allowing full-screen resize, but just by default. So there I could go to real full-screen just by one click.
But anyway, thank you.

Try this out:
Keep the 'don't resize video in fullscreen' option checked and when you've maximized your video press 'M' for movie mode OR 'A' to cycle aspect ratios OR 'O' to auto pan-scan OR 'shift+o' to bring up the custom pan-scan window. See if one of these actions works for you. You will need to press 'esc' and then go back to full-screen to restore your video's original size, but that is just a mild inconvenience.