MidiGlass is an old program (started in 1999) that shows, alters and plays midi files.
If you want to use SoundFont copy the .dll files from
https://github.com/Ian-Macallan/MidiGlass/tree/main/fluidsynth-2.3.4-win10-x64/bin
or
https://github.com/Ian-Macallan/MidiGlass/tree/main/fluidsynth-2.3.4-winXP-x86/bin
according to the version you use, and search Sound Font (.sf2) on the internet.
To use Soundfonts first check the box and select the directory where .sf2 are.
Second in the instrument column just enter the name of the Soundfont.
The Event In Track will show the Instrument.
Macallan