As an aside to the scheme issue, I just found that if I add in a
Fl::get_system_colors();
(I put it after the make_current())
and then added the following to .Xdefaults:
dillo*background: red
dillo*foreground: yellow
Then dillo's dialogs, and certain parts of the UI, and -- interestingly --
the default text color on pages, well, it all turns rather red&yellow in
general.
The src talks about KDE, at least, setting those values in xrdb.
If it should happen that many of the various desktop environments set
these values, getting this all to work reasonably correctly might be
pleasing to everyone nowadays who expects all of their windows to
look similar. People are very first-impression ("It's ugly!" *deletes*)...