First post, by truth_deleted
Attached two patches and a win32 binary of DOSBox-0.74/SVN for testing. The opengl patch is to center the fullscreen view while the height is less than 480 pixels; the width is not adjusted. The attached test binary incorporates this change; includes output=opengl and openglnb.
The voodoo patch centers the view (x & y) while the 3dfx resolution is less than 640x480; this worked in EF2000+3dfx (640x400) using a 4:3 LCD screen - hopefully it will work with a widescreen monitor and with a Windows guest OS. However, this code edit is not testable via this SVN-only binary.
I made these minor edits so that fullscreen openGL view is centered on the LCD screen for games of interest. It will require further changes to center other games properly.