common_windows.c

// 17 july 2014

#include "winapi_windows.h"
#include "_cgo_export.h"

BOOL sharedWndProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam, LRESULT *lResult)
{
	*lResult = (LRESULT) hollowBrush;
	return TRUE;
}

common_windows.go

// 12 july 2014

package ui

import (
	"fmt"
)

// #cgo CFLAGS: --std=c99
// #cgo LDFLAGS: -luser32 -lkernel32 -lgdi32 -luxtheme -lmsimg32 -lcomdlg32
// #include "winapi_windows.h"
import "C"

//export xmissedmsg
func xmissedmsg(purpose *C.char, f *C.char, uMsg C.UINT) {
	panic(fmt.Errorf("%s window procedure message %d does not return a value (bug in %s)", C.GoString(purpose), uMsg, C.GoString(f)))
}

init_windows.c

// 17 july 2014

#include "winapi_windows.h"

HBRUSH hollowBrush;

DWORD initWindows(char **errmsg)
{
	hollowBrush = GetStockObject(HOLLOW_BRUSH);
	if (hollowBrush == NULL) {
		*errmsg = "error getting hollow brush";
		return GetLastError();
	}

	return 0;
}

winapi_windows.h

// 17 july 2014

// cgo will include this file multiple times
#ifndef __GO_UI_WINAPI_WINDOWS_H__
#define __GO_UI_WINAPI_WINDOWS_H__

#define UNICODE
#define _UNICODE
#define STRICT
#define STRICT_TYPED_ITEMIDS
// get Windows version right; right now Windows XP
#define WINVER 0x0501
#define _WIN32_WINNT 0x0501
#define _WIN32_WINDOWS 0x0501		/* according to Microsoft's winperf.h */
#define _WIN32_IE 0x0600			/* according to Microsoft's sdkddkver.h */
#define NTDDI_VERSION 0x05010000	/* according to Microsoft's sdkddkver.h */
#include <windows.h>
#include <commctrl.h>
#include <stdint.h>
#include <uxtheme.h>
#include <string.h>
#include <wchar.h>
#include <windowsx.h>
#include <vsstyle.h>
#include <vssym32.h>

// init_windows.c
extern HBRUSH hollowBrush;
extern DWORD initWindows(char **);

// common_windows.c
extern BOOL sharedWndProc(HWND, UINT, WPARAM, LPARAM, LRESULT *);

#endif

zz_test.go

// 8 july 2014

package ui

// This file is called zz_test.go to keep it separate from the other files in this package (and because go test won't accept just test.go)

import (
	"testing"
)

func TestDummy(t *testing.T) {
	// do nothing
}