Let's look at a shareware shovelware compilation which was a highly formative experience in my understanding of what computer games are and could be. I'm aware that the DOSBox window changes sizes several times, because different games run at different resolutions. Thus, while I'm playing Aldo's Adventure, you can see part of my Windows desktop peeking out (hello Fallout, Cave Story, and GTA: San Andreas!) while on two other games the bottom part of the game screen is cut off. I don't know what can be done about this, since I can't change the resolution of the video itself on-the-fly, and I don't know of any way to force the DOSBox window to remain a certain size. (The auto-scaling with the game's resolution is supposed to be a feature, not a bug.) We might just have to live with it. Sorry!
Games shown in this video:
Aldo's Adventure
B17 Pinball
Bandit
Blue Balls
65