2) Install dependencies for gtk compilation
./install_sysdeps.sh
At least on fedora, this automatically installs everything you need to build gtk from sources and being able to compile swt glue code.
On non-fedora, it prints required packages. (ubuntu..) and you can install them manually with your package manager.
(non-fedora contributions are welcome).
3) Rebuild swt natives
./rebuild_swt_natives.sh
This is the script you'd probably be running many times a day.
This automatically rebuilds swt native code and puts it into your swt binary folder. For both,gtk2 and gtk3. It builds them with debugging support, you you can set breakpoints in os_custom.c and debug the native code (yay).
It cleans out git binary folder from old .so libs, to avoid wrong libs being loaded during bisect.
It fixes .classpath for swt & snippet project, which helps overcome folder/classpath changes.
Also prints current number of compile warnings :-).
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Each script has instructions at the top and it prints further instructions at the end.
I hope they're helpful.
Please let me know if you have any questions.