diff --git a/examples/open_window.rs b/examples/open_window.rs
index 7a04268..7809817 100755
--- a/examples/open_window.rs
+++ b/examples/open_window.rs
@@ -1,14 +1,10 @@
 use baseview::{Event, Window, WindowHandler, WindowSize, WindowScalePolicy};
 
-struct MyProgram {}
+struct OpenWindowExample;
 
-impl WindowHandler for MyProgram {
+impl WindowHandler for OpenWindowExample {
     type Message = ();
 
-    fn build(_window: &mut Window) -> Self {
-        Self {}
-    }
-
     fn on_frame(&mut self) {}
 
     fn on_event(&mut self, _window: &mut Window, event: Event) {
@@ -35,6 +31,6 @@ fn main() {
         parent: baseview::Parent::None,
     };
 
-    let (handle, _window_info) = Window::open::<MyProgram>(window_open_options).unwrap();
+    let handle = Window::open(window_open_options, |_| OpenWindowExample);
     handle.app_run_blocking();
 }
diff --git a/src/lib.rs b/src/lib.rs
index 2b9b126..c2f855b 100755
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -40,8 +40,6 @@ type WindowOpenResult = Result<WindowInfo, ()>;
 pub trait WindowHandler {
     type Message;
 
-    fn build(window: &mut Window) -> Self;
-
     fn on_frame(&mut self);
     fn on_event(&mut self, window: &mut Window, event: Event);
     fn on_message(&mut self, window: &mut Window, message: Self::Message);
diff --git a/src/macos/window.rs b/src/macos/window.rs
index 6e718ba..e16f5b3 100755
--- a/src/macos/window.rs
+++ b/src/macos/window.rs
@@ -33,7 +33,11 @@ impl WindowHandle {
 }
 
 impl Window {
-    pub fn open<H: WindowHandler>(options: WindowOpenOptions) -> WindowHandle {
+    pub fn open<H, B>(options: WindowOpenOptions, build: B) -> WindowHandle
+        where H: WindowHandler,
+              B: FnOnce(&mut Window) -> H,
+              B: Send + 'static
+    {
         unsafe {
             let _pool = NSAutoreleasePool::new(nil);
 
@@ -59,7 +63,7 @@ impl Window {
 
             let mut window = Window { ns_window, ns_view };
 
-            let handler = H::build(&mut window);
+            let handler = build(&mut window);
 
             // FIXME: only do this in the unparented case
             let current_app = NSRunningApplication::currentApplication(nil);
diff --git a/src/win/window.rs b/src/win/window.rs
index a2bf4f6..c74e7d4 100755
--- a/src/win/window.rs
+++ b/src/win/window.rs
@@ -173,7 +173,11 @@ impl WindowHandle {
 }
 
 impl Window {
-    pub fn open<H: WindowHandler>(options: WindowOpenOptions) -> Result<(WindowHandle, WindowInfo), ()> {
+    pub fn open<H, B>(options: WindowOpenOptions, build: B) -> WindowHandle
+        where H: WindowHandler,
+              B: FnOnce(&mut Window) -> H,
+              B: Send + 'static
+    {
         unsafe {
             let title = (options.title.to_owned() + "\0").as_ptr() as *const i8;
 
@@ -239,7 +243,7 @@ impl Window {
 
             let mut window = Window { hwnd };
 
-            let handler = H::build(&mut window);
+            let handler = build(&mut window);
 
             let window_state = Box::new(RefCell::new(WindowState {
                 window_class,
diff --git a/src/x11/window.rs b/src/x11/window.rs
index f7df37a..a6eeb21 100755
--- a/src/x11/window.rs
+++ b/src/x11/window.rs
@@ -40,11 +40,15 @@ impl WindowHandle {
 }
 
 impl Window {
-    pub fn open<H: WindowHandler>(options: WindowOpenOptions) -> Result<(WindowHandle, WindowInfo), ()> {
+    pub fn open<H, B>(options: WindowOpenOptions, build: B) -> WindowHandle
+        where H: WindowHandler,
+              B: FnOnce(&mut Window) -> H,
+              B: Send + 'static
+    {
         let (tx, rx) = mpsc::sync_channel::<WindowOpenResult>(1);
 
         let thread = thread::spawn(move || {
-            if let Err(e) = Self::window_thread::<H>(options, tx.clone()) {
+            if let Err(e) = Self::window_thread::<H, B>(options, build, tx.clone()) {
                 let _ = tx.send(Err(e));
             }
         });
@@ -55,9 +59,12 @@ impl Window {
         Ok((WindowHandle { thread }, window_info))
     }
 
-    fn window_thread<H: WindowHandler>(
-        options: WindowOpenOptions, tx: mpsc::SyncSender<WindowOpenResult>,
-    ) -> WindowOpenResult {
+    fn window_thread<H, B>(options: WindowOpenOptions, build: B,
+        tx: mpsc::SyncSender<WindowOpenResult>) -> WindowOpenResult
+        where H: WindowHandler,
+              B: FnOnce(&mut Window) -> H,
+              B: Send + 'static
+    {
         // Connect to the X server
         // FIXME: baseview error type instead of unwrap()
         let xcb_connection = XcbConnection::new().unwrap();
@@ -168,7 +175,7 @@ impl Window {
             new_physical_size: None,
         };
 
-        let mut handler = H::build(&mut window);
+        let mut handler = build(&mut window);
 
         let _ = tx.send(Ok(window_info));