Added OS X building. Go 1.5 required because of https://github.com/golang/go/issues/9411 which affects this. Also set up proper multithreading on OS X. Currently crashes due to similar issue I've had with libui.

README.md

@@ -10,7 +10,7 @@ It runs on/requires:
 - Mac OS X: cgo, Mac OS X 10.7 and newer
 - other Unixes: cgo, GTK+ 3.4 and newer
 
-TODO figure out the minimum required version of Go
+It also requires Go 1.5 or newer (due to various bugs in cgo that were fixed only starting with 1.5).
 
 (this README needs some work)
 

link_darwin.go

@@ -0,0 +1,22 @@
+// 13 december 2015
+
+package ui
+
+// #cgo LDFLAGS: -L${SRCDIR} -lui -framework CoreFoundation -lpthread
+// #include <CoreFoundation/CoreFoundation.h>
+// #include <pthread.h>
+// extern void _CFRunLoopSetCurrent(CFRunLoopRef);
+// extern pthread_t _CFMainPThread;
+import "C"
+
+// OS X cares very deeply if we don't run on the very first thread the OS creates
+// why? who knows. it's stupid and completely indefensible. let's use undocumented APIs to get around it.
+// apple uses them too: http://www.opensource.apple.com/source/kext_tools/kext_tools-19.2/kextd_main.c?txt
+// apple HAS SUGGESTED them too: http://lists.apple.com/archives/darwin-development/2002/Sep/msg00250.html
+// gstreamer uses them too: http://cgit.freedesktop.org/gstreamer/gst-plugins-good/tree/sys/osxvideo/osxvideosink.m
+func ensureMainThread() {
+	// TODO set to nil like the apple code?
+	C._CFRunLoopSetCurrent(C.CFRunLoopGetMain())
+	// TODO is this part necessary?
+	C._CFMainPThread = C.pthread_self()
+}

link_unix.go

@@ -7,3 +7,7 @@ package ui
 
 // #cgo LDFLAGS: -L${SRCDIR} -lui -Wl,-rpath=$ORIGIN
 import "C"
+
+func ensureMainThread() {
+	// do nothing; GTK+ doesn't care which thread we're on so long as we don't change it after starting
+}

link_windows.go

@@ -4,3 +4,7 @@ package ui
 
 // #cgo LDFLAGS: -L${SRCDIR} -lui
 import "C"
+
+func ensureMainThread() {
+	// do nothing; Windows doesn't care which thread we're on so long as we don't change it after starting
+}

main.go

@@ -40,7 +40,7 @@ func Main(f func()) error {
 func start(errchan chan error, f func()) {
 	runtime.LockOSThread()
 
-	// TODO set main thread on OS X
+	ensureMainThread()
 
 	// TODO HEAP SAFETY
 	opts := C.uiInitOptions{}