Monospace postscript bit not set on sfd2ufo conversion

[mitradranirban]

For Monospace fonts UFO should have the following in fontdata.plist

    <key>postscriptIsFixedPitch</key>
    <true/>

However when I export my monospace font such setting is not created

[khaledhosny]

There does not seem to be anything related to fixed pitch in https://fontforge.org/docs/techref/sfdformat.html, so I’m not sure if FontForge saves this to the SFD file (it might be detecting monospaceness at runtime by examining glyph advances), but if you know how it is saved to the SFD file, it should be easy enough to support.