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/windows/util.rs

@@ -1,4 +1,9 @@
-use windows::Win32::Foundation::{LPARAM, WPARAM};
+use windows::Win32::{
+    Foundation::{HWND, LPARAM, WPARAM},
+    UI::WindowsAndMessaging::{
+        GetWindowLongPtrW, GetWindowLongW, SetWindowLongPtrW, SetWindowLongW, WINDOW_LONG_PTR_INDEX,
+    },
+};
 
 pub(crate) trait HiLoWord {
     fn hiword(&self) -> u16;
@@ -42,3 +47,29 @@ impl HiLoWord for LPARAM {
         (self.0 & 0xFFFF) as i16
     }
 }
+
+pub(crate) unsafe fn get_window_long(hwnd: HWND, nindex: WINDOW_LONG_PTR_INDEX) -> isize {
+    #[cfg(target_pointer_width = "64")]
+    unsafe {
+        GetWindowLongPtrW(hwnd, nindex)
+    }
+    #[cfg(target_pointer_width = "32")]
+    unsafe {
+        GetWindowLongW(hwnd, nindex) as isize
+    }
+}
+
+pub(crate) unsafe fn set_window_long(
+    hwnd: HWND,
+    nindex: WINDOW_LONG_PTR_INDEX,
+    dwnewlong: isize,
+) -> isize {
+    #[cfg(target_pointer_width = "64")]
+    unsafe {
+        SetWindowLongPtrW(hwnd, nindex, dwnewlong)
+    }
+    #[cfg(target_pointer_width = "32")]
+    unsafe {
+        SetWindowLongW(hwnd, nindex, dwnewlong as i32) as isize
+    }
+}