New launcher doesn't let me force resolution

With the old 'Minecraft.exe' launcher, I was able to force 640x480 resolution on Minecraft through Windows' compatibility mode; this would crop my entire screen so I could play full-screen at 640x480 resolution.

When I try to do this on the new launcher, it starts up, crops to 640x480 for about half a second, then immediately goes back to my computer's native 1600x900 resolution, and the launcher window subsequently opens in it's standard 854x480 resolution.

I can change the resolution through the launcher settings, but this only affects the game's window — the rest of my screen is still in 1600x900, so going into full-screen will set it to that resolution, and I don't want that.

Does anyone know how to get past this? Considering how Minecraft is such a resource intensive game, it's a pretty big issue that you can only play full-screen at your monitor's native resolution.

Steps to reproduce:
• Right click Minecraft shortcut.
• Select 'Properties'.
• Select 'Compatibility' tab.
• Check 'Run in 640 x 480 screen resolution'.
• Start Minecraft Launcher.