Cross-platform titlebar (#9405)

This PR reverts https://github.com/zed-industries/zed/pull/9392 and
fixes the regressions that led to the reversion.

Release Notes:

- N/A

---------

Co-authored-by: Ezekiel Warren <ezekiel@seaube.com>

crates/gpui/src/platform/windows/util.rs

@@ -42,3 +42,29 @@ 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
+    }
+}