I'm trying to play Grand Theft Auto: San Andreas (v1.01) at a 4:3 resolution on my 16:9 (1080p) monitor. The resolution I select in-game is 1400x1050 (4:3). However, when I do this, the game stretches to fill the whole screen - this look ugly, and I would much prefer the black bars on the sides of the game.
In Radeon settings, I have GPU scaling enabled, and the scaling mode is set to preserve aspect ratio. I also tried setting it to center, to no avail. It's acting like it's always "full panel", regardless of what I actually set it to.
The game is running in fullscreen mode (since there is no other option). I'm running driver version 17.5.2 on Windows 10 with an RX 480. This issue also happens on driver version 17.4.2 (might be off by one or two versions); I only updated to the most recent version to see if it would solve this problem, and it didn't.