More of the previous error and not printing panics... derp me. Still not fixed yet though...

main.go

@@ -4,7 +4,10 @@ package main
 func main() {
 	w := NewWindow("Main Window")
 	w.Closing = make(chan struct{})
-	w.Open()
+	err := w.Open()
+	if err != nil {
+		panic(err)
+	}
 	<-w.Closing
 	w.Close()
 }

sysdata_windows.go

@@ -60,7 +60,7 @@ func (s *sysData) make() (err error) {
 		ret:	ret,
 	}
 	r := <-ret
-	if r.err != nil {
+	if r.ret == 0 {		// failure
 		return r.err
 	}
 	s.hwnd = _HWND(r.ret)