Windows – way to make VirtualBox use a specific monitor when going full-screen

I'm gonna make the bold assumption that your problem lies with wine-based applications (e.g. Adobe Reader). One solution is to create a window for wine that covers the exact resolution of display B. First run winecfg, next select 'Graphics' tab, following which, tick ‘emulate a virtual desktop’ and enter the resolution of Display B. Now you can move this window to cover Display B and fullscreen the operation within the window. The only small issue is a small buffer region made by the border of the window.

Windows 7 (and I believe Vista) doesn't support the full-screen feature for MS-DOS or Command Prompt console. It doesn't even allow full-screen when using the Command Prompt via Windows 7's Windows XP Mode. On Windows XP, it can be set to full screen via Alt + Enter or right-clicking the console title bar and selecting Full Screen.

A possible workaround on Windows 7: With Command Prompt open, right click the console title bar, then select Properties. Within the Layout tab, you can adjust the width and height. My suggestion is: Adjust only the width to match the width of your screen. Once the adjustments are made, double click the console title bar. Using this workaround gives it the closest full-screen effect that can be achieved.