First post, by videogamer555
I tested this with the latest vanilla SVN Windows version (r4022, at the time of me writing this), that I downloaded from DOSBox EmuCR, as well as the standard release version of (0.74, at the time of me writing this). The video output mode I tested it in was Surface. Scaler was set to none (so only standard screen stretching was applied). Aspect Ratio was set to False (so pixel aspect ratio is 1:1). Note, that I didn't run any program that switched into graphics modes, nor 40x25 text mode, so I have only tested its behavior in standard text mode (80x25), which is the default mode DOSBox starts in (just like normal DOS).
When using the following display types (referred to as "machine" types in DOSBox), the DosBox screen is properly stretched to fit your screen:
CGA
Tandy
PCJr
SVGA_S3
SVGA_ET3000
SVGA_ET4000
SVGA_Paradise
VESA_NoLFB
VESA_OldVBE
It does not stretch completely (there's a gap at the top and bottom of the screen) when using the following display types:
Hercules
EGA
VGAOnly
So same problem exists for the standard DOSBox release version (0.74), and has not been corrected as of SVN version 4022.
I wanted to also test it with aspect ratio set to true, but it doesn't work in text modes with release version 0.74, and even in SVN version r4022 it doesn't work in text modes on all display types (for example EGA, when in text mode, with aspect set to true it still behaves just as if aspect ratio was still set to false).