But I found that multi-threading tutorials don't. According to SDL documentation, SDL isn't thread-safe on Linux, if you don't use X11's multi-threading capabilities. So you have to add something to the tutorial code to work.
For example for tutorial 33's code insert these:
- {l Code}: {l Select All Code}
8 #include <X11/Xlib.h>
76 //Initialize X11 multithreading
77 XInitThreads();
Then they should work.