It is still very early days but I've (finally) got around to starting to rewrite my original emulator in C using Xlib. I've not worked out how to use a bit map for the symbols on the keys so I'm restricted by the available fonts.
I'm finding that it is a bit of a steep learning curve (for someone who has never used C much before now - this is only my 5th C program), made slightly more difficult by making the source code 'portable' between systems, but I think I'm starting to get the hang of it.
Screenshots below show emulators running under GNOME and Motif. I like the aspect ratios of the buttons as they are but I'm trying to decide if I should make them slightly higher and wider to allow me to use the same font for both the alternate function labels (blue) and the shifted funtion labels (yellow).
I thought about using ATAN or ACOSH instead of TAN-1 or COSH-1 to save one character, but decided to stick with the 'original' format for now...
Comments welcome - Mike T.
Edited: 23 June 2013, 6:56 p.m. after one or more responses were posted