diff --git a/redo/zwinconstgen.go b/redo/zwinconstgen.go
new file mode 100644
index 0000000..1df9bd9
--- /dev/null
+++ b/redo/zwinconstgen.go
@@ -0,0 +1,230 @@
+// +build ignore
+
+// 24 may 2014
+package main
+
+import (
+	"fmt"
+	"os"
+	"strings"
+	"go/token"
+	"go/ast"
+	"go/parser"
+	"sort"
+	"io/ioutil"
+	"path/filepath"
+	"os/exec"
+)
+
+func getPackage(path string) (pkg *ast.Package) {
+	fileset := token.NewFileSet()		// parser.ParseDir() actually writes to this; not sure why it doesn't return one instead
+	filter := func(i os.FileInfo) bool {
+		return strings.HasSuffix(i.Name(), "_windows.go")
+	}
+	pkgs, err := parser.ParseDir(fileset, path, filter, parser.AllErrors)
+	if err != nil {
+		panic(err)
+	}
+	if len(pkgs) != 1 {
+		panic("more than one package found")
+	}
+	for k, _ := range pkgs {		// get the sole key
+		pkg = pkgs[k]
+	}
+	return pkg
+}
+
+type walker struct {
+	desired	func(string) bool
+}
+
+var known = map[string]string{}
+var unknown = map[string]struct{}{}
+
+func (w *walker) Visit(node ast.Node) ast.Visitor {
+	switch n := node.(type) {
+	case *ast.Ident:			// constant or structure?
+		if w.desired(n.Name) {
+			if n.Obj != nil {
+				delete(unknown, n.Name)
+				kind := n.Obj.Kind.String()
+				if known[n.Name] != "" && known[n.Name] != kind {
+					panic(n.Name + "(" + kind + ") already known to be a " + known[n.Name])
+				}
+				known[n.Name] = kind
+			} else if _, ok := known[n.Name]; !ok {		// only if not known
+				unknown[n.Name] = struct{}{}
+			}
+		}
+	case *ast.Comment:		// function?
+		// TODO
+	}
+	return w
+}
+
+func gatherNames(pkg *ast.Package) {
+	desired := func(name string) bool {
+		return strings.HasPrefix(name, "c_") ||		// constants
+			strings.HasPrefix(name, "s_")			// structs
+	}
+	for _, f := range pkg.Files {
+		for _, d := range f.Decls {
+			ast.Walk(&walker{desired}, d)
+		}
+	}
+}
+
+// for backwards compatibiilty reasons, Windows defines GetWindowLongPtr()/SetWindowLongPtr() as a macro which expands to GetWindowLong()/SetWindowLong() on 32-bit systems
+// we'll just simulate that here
+var gwlpNames = map[string]string{
+	"386":		"etWindowLongW",
+	"amd64":		"etWindowLongPtrW",
+}
+
+func writeLine(f *os.File, line string) {
+	fmt.Fprintf(f, "%s\n", line)
+}
+
+const cgopreamble = `
+#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>
+`
+
+func writeConstCast(f *os.File, c string) {
+	cc := c[2:]		// strip leading c_
+	fmt.Fprintf(f, "uintptr_t %s = (uintptr_t) (%s);\n", c, cc)
+}
+
+func writeConstPrint(f *os.File, c string) {
+	fmt.Fprintf(f, "\tfmt.Fprintf(buf, \"const %%s = %%d\\n\", %q, C.%s)\n", c, c)
+}
+
+func writeStructPrint(f *os.File, s string) {
+	cs := s[2:]		// strip leading s_
+	fmt.Fprintf(f, "\tt = reflect.TypeOf(C.%s{})\n", cs)
+	// TODO
+}
+
+func main() {
+	if len(os.Args) < 3 {
+		panic("usage: " + os.Args[0] + " path goarch [go-command-options...]")
+	}
+	pkgpath := os.Args[1]
+	targetarch := os.Args[2]
+	if _, ok := gwlpNames[targetarch]; !ok {
+		panic("unknown target windows/" + targetarch)
+	}
+	goopts := os.Args[3:]		// valid if len(os.Args) == 3; in that case this will just be a slice of length zero
+
+	pkg := getPackage(pkgpath)
+	gatherNames(pkg)
+
+	// if we still have some known, I didn't clean things up completely
+	if len(known) > 0 {
+		knowns := ""
+		for ident, kind := range known {
+			if kind != "var" && kind != "const" {
+				continue
+			}
+			knowns += "\n" + ident + " (" + kind + ")"
+		}
+		panic("error: the following are still known!" + knowns)		// has a newline already
+	}
+
+	// keep sorted for git
+	consts := make([]string, 0, len(unknown))
+	structs := make([]string, 0, len(unknown))
+	for ident, _ := range unknown {
+		if strings.HasPrefix(ident, "s_") {
+			structs = append(structs, ident)
+			continue
+		}
+		consts = append(consts, ident)
+	}
+	sort.Strings(consts)
+	sort.Strings(structs)
+
+	// thanks to james4k in irc.freenode.net/#go-nuts
+	tmpdir, err := ioutil.TempDir("", "windowsconstgen")
+	if err != nil {
+		panic(err)
+	}
+	genoutname := filepath.Join(tmpdir, "gen.go")
+	f, err := os.Create(genoutname)
+	if err != nil {
+		panic(err)
+	}
+
+	writeLine(f, "package main")
+	writeLine(f, "import \"fmt\"")
+	writeLine(f, "import \"bytes\"")
+	writeLine(f, "import \"runtime\"")
+	writeLine(f, "import \"go/format\"")
+	writeLine(f, "/*")
+	writeLine(f, cgopreamble)
+	for _, const := range consts {
+		writeConstCast(f, const)
+	}
+	writeLine(f, "*/")
+	writeLine(f, "import \"C\")
+	writeLine(f, "func main() {")
+	writeLine(f, "\tbuf := new(bytes.Buffer)")
+	writeLine(f, "\tfmt.Fprintln(buf, \"package main\")")
+	writeLine(f, "\tfmt.Fprintln(buf, \"func main() {\")")
+	for _, c := range consts {
+		writeConstPrint(f, c)
+	}
+	writeLine(f, "\tfmt.Fprintln(buf, \"var t reflect.Type\")")
+	writeLine(f, "\tfmt.Fprintln(buf, \"var s string\")")
+	for _, s := range structs {
+		writeStructPrint(f, s)
+	}
+	writeLine(f, "\tfmt.Fprintln(buf, \"}\")")
+	writeLine(f, "\tres, err := format.Source(buf.Bytes())")
+	writeLine(f, "\tif err != nil { panic(err) }")
+	wrtieLine(f, "\tfmt.Printf(\"%s\", res)")
+	writeLine(f, "}")
+
+	cmd := exec.Command("go", "run")
+	cmd.Args = append(cmd.Args, goopts...)		// valid if len(goopts) == 0; in that case this will just be a no-op
+	cmd.Args = append(cmd.Args, genoutname)
+	f, err = os.Create(filepath.Join(pkgpath, "zconstants_windows_" + targetarch + ".go"))
+	if err != nil {
+		panic(err)
+	}
+	defer f.Close()
+	cmd.Stdout = f
+	cmd.Stderr = os.Stderr
+	// we need to preserve the environment EXCEPT FOR the variables we're overriding
+	// thanks to raggi and smw in irc.freenode.net/#go-nuts
+	for _, ev := range os.Environ() {
+		if strings.HasPrefix(ev, "GOOS=") ||
+			strings.HasPrefix(ev, "GOARCH=") ||
+			strings.HasPrefix(ev, "CGO_ENABLED=") {
+			continue
+		}
+		cmd.Env = append(cmd.Env, ev)
+	}
+	cmd.Env = append(cmd.Env,
+		"GOOS=windows",
+		"GOARCH=" + targetarch,
+		"CGO_ENABLED=1")		// needed as it's not set by default in cross-compiles
+	err = cmd.Run()
+	if err != nil {
+		// TODO find a way to get the exit code
+		os.Exit(1)
+	}
+
+	// TODO remove the temporary directory
+}