Fred, I just tried this: Hold down the option key when launching my app. Choose "Set Window width" from the menu. Set it to 100 and click OK. When the app starts up, I can run editor.exe and it fills the window - 100 columns wide. This seems to do what you want. There's also a built-in command that you can run from autoexec.bat or at the command line (this is in my build, but not in standard DOSBox-X, unless I'm misremembering): 90x43 However, for reasons that I don't pretend to understand, this will give you a 90-column XyWrite window only if you've modified the BC line so that it reads 90 instead of 80 - while, with the other method described above, the BC command doesn't need to be changed. Again, I don't pretend to understand this. Enter HELP at the command line for some other format-setting commands.