document which thread each call is coming from

library/Hooks.cpp

@@ -1,33 +1,35 @@
 #include "Core.h"
 #include "Export.h"
 
-// called before main event loop starts
+// called from the main thread before the simulation thread is started
+// and the main event loop is initiated
 DFhackCExport void dfhooks_init() {
     // TODO: initialize things we need to do while still in the main thread
 }
 
-// called after main event loops exits
+// called from the main thread after the main event loops exits
 DFhackCExport void dfhooks_shutdown() {
     DFHack::Core::getInstance().Shutdown();
 }
 
-// called in the main event loop
+// called from the simulation thread in the main event loop
 DFhackCExport void dfhooks_update() {
     DFHack::Core::getInstance().Update();
 }
 
-// called just before adding the macro recording/playback overlay
+// called from the simulation thread just before adding the macro
+// recording/playback overlay
 DFhackCExport void dfhooks_prerender() {
     // TODO: render overlay widgets that are not attached to a viewscreen
 }
 
-// called for each SDL event, if true is returned, then the event has been
-// consumed and further processing shouldn't happen
+// called from the main thread for each SDL event. if true is returned, then
+// the event has been consumed and further processing shouldn't happen
 DFhackCExport bool dfhooks_sdl_event(SDL::Event* event) {
     return DFHack::Core::getInstance().DFH_SDL_Event(event);
 }
 
-// called for each utf-8 char read from the ncurses input
+// called from the main thread for each utf-8 char read from the ncurses input
 // key is positive for ncurses keys and negative for everything else
 // if true is returned, then the event has been consumed and further processing
 // shouldn't happen