Fix other

pkg/windows/windows.go

@@ -1,6 +1,7 @@
 package windows
 
 import (
+	"os"
 	"syscall"
 	"unsafe"
 )
@@ -10,8 +11,13 @@ const (
 	MB_OK = 0
 )
 
+func Fatal(title, message string, exitCode int) {
+	messageBox(NULL, message, title, MB_OK)
+	os.Exit(exitCode)
+}
+
 // MessageBox of Win32 API.
-func MessageBox(hwnd uintptr, caption, title string, flags uint) int {
+func messageBox(hwnd uintptr, caption, title string, flags uint) int {
 	_caption, err := syscall.UTF16PtrFromString(caption)
 	if err != nil {
 		panic(err)