Things you can do if you want to help improve DosGlk:

DosGlk isn't as robust as it could be.  It should do more careful
checking of parameters to various functions, and it should be
audited to make sure it behaves well when it runs out of memory.

DosGlk uses more memory than it probably should, especially in the
smaller 16-bit memory models.

Commandline history would be nice.

Some sort of file selection dialog would be nice.

We should do something about associating file types with filename
extensions.  DosGlk doesn't do anything like that yet.

Support for mouse events would be nice.

A graphical mode with antialiased proportional fonts would make reading
text from DosGlk programs much easier on the eyes.