@crumb
there are threads over threads on this subject. almost none volunteered. nova looked at it but failed. i cant do it. artur cant do it. if someone just did it instead of giving valuable advises we would have it already. bernd suggested to adapt itix mui frontend, but itix will not do it either. so what for all that talk? we get what we can and be content with it.
years ago I did a small tool to create full sourcecode of Reaction GUIs (I didn't know C nor makefiles so real code is in C files...), the tool sources were crap but the generated code was acceptable.
http://sourceforge.net/projects/cuaz/files/latest/downloadxml2reaction was buggy but more or less functional, I could create ready to compile C guis with a gui.c file with main() and all the stuff and an "events.c" file ready to fill by the user (kinda visual basic with all that myButton_Clicked() functions). I then realized that MUI was more elegant and started to write a xml2mui but got bored and forgot about it. Some time later I looked at the tool sources and I think those are useless. It required expat.library, tons of stack, had memory leaks everywhere, null pointers and it probably won't work on os4. it worked on morphos 1.4.x thought (iirc I even did a native version, it was kinda funny because MorphOS lacks real Reaction and I used OS3.9 Reaction for that). If you want to learn to write Reaction guis fast the generated sources may help you. Look inside xml/ directory and you'll find some examples. There's even an xml/ide.xml that defines ide.c and an events.c file that can build ide.exe file, if you launch it you'll see an example app with menus. I also did small guis for my own basiliskII for os4 (i had hangs handling the hardfiles in the gui so that's the reason I never released it), etc... nowadays I lack time to code.
My advise is using the OS4 port as base and not the SDL one. And about ixemul... get rid of it, specially the nasty 6x versions