diff --git a/redo/dialog_darwin.go b/redo/dialog_darwin.go
index 9e65714..f1882a8 100644
--- a/redo/dialog_darwin.go
+++ b/redo/dialog_darwin.go
@@ -9,11 +9,17 @@ import (
 // #include "objc_darwin.h"
 import "C"
 
-func openFile() string {
-	fname := C.openFile()
+func (w *window) openFile(f func(filename string)) {
+	C.openFile(w.id, unsafe.Pointer(&f))
+}
+
+//export finishOpenFile
+func finishOpenFile(fname *C.char, data unsafe.Pointer) {
+	f := (*func(string))(data)
 	if fname == nil {
-		return ""
+		(*f)("")
+		return
 	}
 	defer C.free(unsafe.Pointer(fname))
-	return C.GoString(fname)
+	(*f)(C.GoString(fname))
 }
diff --git a/redo/dialog_darwin.m b/redo/dialog_darwin.m
index 0557018..4fb9e3e 100644
--- a/redo/dialog_darwin.m
+++ b/redo/dialog_darwin.m
@@ -3,10 +3,11 @@
 #import "objc_darwin.h"
 #import <Cocoa/Cocoa.h>
 
-char *openFile(void)
+#define toNSWindow(x) ((NSWindow *) (x))
+
+void openFile(id parent, void *data)
 {
 	NSOpenPanel *op;
-	NSInteger ret;
 
 	op = [NSOpenPanel openPanel];
 	[op setCanChooseFiles:YES];
@@ -18,11 +19,12 @@ char *openFile(void)
 	[op setExtensionHidden:NO];
 	[op setAllowsOtherFileTypes:YES];
 	[op setTreatsFilePackagesAsDirectories:YES];
-	beginModal();
-	ret = [op runModal];
-	endModal();
-	if (ret != NSFileHandlingPanelOKButton)
-		return NULL;
-	// string freed on the Go side
-	return strdup([[[op URL] path] UTF8String]);
+	[op beginSheetModalForWindow:toNSWindow(parent) completionHandler:^(NSInteger ret){
+		if (ret != NSFileHandlingPanelOKButton) {
+			finishOpenFile(NULL, data);
+			return;
+		}
+		// string freed on the Go side
+		finishOpenFile(strdup([[[op URL] path] UTF8String]), data);
+	}];
 }
diff --git a/redo/objc_darwin.h b/redo/objc_darwin.h
index d42b806..a8bf282 100644
--- a/redo/objc_darwin.h
+++ b/redo/objc_darwin.h
@@ -141,6 +141,6 @@ extern void disableAutocorrect(id);
 extern id toImageListImage(void *, intptr_t, intptr_t, intptr_t);
 
 /* dialog_darwin.m */
-extern char *openFile(void);
+extern void openFile(id, void *);
 
 #endif