How to let full-screen be on specific monitor?
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.