If you need to display UTF8 and antialiased fonts from HTML in your Motif application, you can use updated version of XmHTML.
It was dormant for 10 years, but since Motif is now UFT8 and XFT capable, we had to fix XmHTML in order to continue to use it.
License is LGPL so you can use it in your commercial projects.
Works on Linux and OS X.
Sourceforge site has the screenshots.
The extra Motif widgets used on original Netscape navigator continue to be used in nedit.
Arahne is using them in its textile CAD system, and as we needed to switch to UTF8 and XFT antialiased fonts, we added those features and released changes under original open source license.
I can highly recommend XmLGrid widget, it is capable of displaying a table of 1.000.000 lines without any problems, scrolling, sorting, everything is immediate.
Memory footprint is also very moderate, as table contents is stored as very compact string, not as a million of separate widgets.
https://sourceforge.net/projects/microline/