windows: better looking titlebar (#9053)

~~work in progress. not ready for review. made for visibility only, but
feel free to comment :)~~

TODO:
- [x] add close/min/max buttons (to be rendered with gpui)
- [x] snap layout support
- [x] fix issues with clicking items in titlebar
- [x] cleanup/document

Release Notes:

- Added custom windows titlebar

![](https://media.discordapp.net/attachments/1208481909676576818/1216985375969378324/caption-buttons-working.gif?ex=660260f4&is=65efebf4&hm=53a17af6e2f233eba54302a5adb9efe23900f4d6f6d1d854bec887120789130c&=)

---------

Co-authored-by: Mikayla <mikayla@zed.dev>

crates/gpui/src/platform/test/window.rs

@@ -1,7 +1,7 @@
 use crate::{
-    AnyWindowHandle, AtlasKey, AtlasTextureId, AtlasTile, Bounds, GlobalPixels, Pixels,
-    PlatformAtlas, PlatformDisplay, PlatformInput, PlatformInputHandler, PlatformWindow, Point,
-    Size, TestPlatform, TileId, WindowAppearance, WindowParams,
+    AnyWindowHandle, AtlasKey, AtlasTextureId, AtlasTile, Bounds, DispatchEventResult,
+    GlobalPixels, Pixels, PlatformAtlas, PlatformDisplay, PlatformInput, PlatformInputHandler,
+    PlatformWindow, Point, Size, TestPlatform, TileId, WindowAppearance, WindowParams,
 };
 use collections::HashMap;
 use parking_lot::Mutex;
@@ -20,7 +20,7 @@ pub(crate) struct TestWindowState {
     platform: Weak<TestPlatform>,
     sprite_atlas: Arc<dyn PlatformAtlas>,
     pub(crate) should_close_handler: Option<Box<dyn FnMut() -> bool>>,
-    input_callback: Option<Box<dyn FnMut(PlatformInput) -> bool>>,
+    input_callback: Option<Box<dyn FnMut(PlatformInput) -> DispatchEventResult>>,
     active_status_change_callback: Option<Box<dyn FnMut(bool)>>,
     resize_callback: Option<Box<dyn FnMut(Size<Pixels>, f32)>>,
     moved_callback: Option<Box<dyn FnMut()>>,
@@ -102,7 +102,7 @@ impl TestWindow {
         drop(lock);
         let result = callback(event);
         self.0.lock().input_callback = Some(callback);
-        result
+        !result.propagate
     }
 }
 
@@ -111,6 +111,10 @@ impl PlatformWindow for TestWindow {
         self.0.lock().bounds
     }
 
+    fn is_maximized(&self) -> bool {
+        unimplemented!()
+    }
+
     fn content_size(&self) -> Size<Pixels> {
         self.bounds().size.into()
     }
@@ -120,7 +124,7 @@ impl PlatformWindow for TestWindow {
     }
 
     fn titlebar_height(&self) -> Pixels {
-        unimplemented!()
+        32.0.into()
     }
 
     fn appearance(&self) -> WindowAppearance {
@@ -208,7 +212,7 @@ impl PlatformWindow for TestWindow {
 
     fn on_request_frame(&self, _callback: Box<dyn FnMut()>) {}
 
-    fn on_input(&self, callback: Box<dyn FnMut(crate::PlatformInput) -> bool>) {
+    fn on_input(&self, callback: Box<dyn FnMut(crate::PlatformInput) -> DispatchEventResult>) {
         self.0.lock().input_callback = Some(callback)
     }