Platform: add bring-all-to-front() function

Adds `Platform.bring-all-to-front()` to the Slint language, lowered to
a new `BuiltinFunction::BringAllToFront` via the platform-lowering pass.

On macOS the function calls `[NSApp arrangeInFront:]` via a free function
in `i-slint-core`, using the `objc2-app-kit` dependency that was already
present for the system tray. On all other platforms it is a no-op.

Public-language API only — no `slint::Window::bring_all_to_front()`,
no `WindowAdapter` trait method, and no language-binding wrappers.
The C FFI entry point (`slint_bring_all_to_front`) is private_api,
used only by generated C++ code.

Addresses the review feedback from PR #11692:
- ogoffart: remove from WindowAdapter trait, implement as free function
  in i-slint-core using objc2-app-kit directly
- ogoffart: no public Rust/C++/JS Window::bring_all_to_front() API
- Both reviewers: split into its own PR (orthogonal to minimize/maximize/close)

Author: tilladam

api/cpp/include/slint.h

@@ -349,6 +349,11 @@ inline bool open_url(const SharedString &url, const WindowAdapterRc &window_adap
     return cbindgen_private::slint_open_url(&url, &window_adapter.handle());
 }
 
+inline void bring_all_to_front()
+{
+    cbindgen_private::slint_bring_all_to_front();
+}
+
 inline SharedString translate_from_bundle(std::span<const char8_t *const> strs,
                                           cbindgen_private::Slice<SharedString> arguments)
 {

api/cpp/lib.rs

@@ -276,6 +276,11 @@ pub unsafe extern "C" fn slint_open_url(
     i_slint_core::open_url(url, window_adapter.window()).is_ok()
 }
 
+#[unsafe(no_mangle)]
+pub extern "C" fn slint_bring_all_to_front() {
+    i_slint_core::bring_all_to_front()
+}
+
 #[unsafe(no_mangle)]
 pub extern "C" fn slint_string_to_styled_text(text: &SharedString, out: &mut StyledText) {
     *out = i_slint_core::styled_text::string_to_styled_text(text.to_string());

api/rs/slint/private_unstable_api.rs

@@ -198,6 +198,7 @@ pub mod re_exports {
     };
     pub use i_slint_core::menus::{Menu, MenuFromItemTree, MenuVTable};
     pub use i_slint_core::model::*;
+    pub use i_slint_core::bring_all_to_front;
     pub use i_slint_core::open_url;
     pub use i_slint_core::properties::{
         ChangeTracker, Property, PropertyTracker, StateInfo, set_state_binding,

internal/compiler/builtins.slint

@@ -2562,6 +2562,13 @@ export global Platform {
     /// }
     /// ```
     function open-url(url: string) -> bool { return false; }
+    /// Brings all application windows to the front of the screen.
+    ///
+    /// On macOS this invokes `[NSApp arrangeInFront:]`, which raises every application window
+    /// to the top of the window stack. On other platforms this function is a no-op.
+    ///
+    /// This corresponds to the standard macOS **Window › Bring All to Front** menu item.
+    function bring-all-to-front() { }
 }
 
 export component NativeButton {

internal/compiler/expression_tree.rs

@@ -123,6 +123,7 @@ pub enum BuiltinFunction {
     StopTimer,
     RestartTimer,
     OpenUrl,
+    BringAllToFront,
     ParseMarkdown,
     StringToStyledText,
 }
@@ -303,6 +304,7 @@ declare_builtin_function_types!(
     ParseMarkdown: (Type::String, Type::Array(Type::StyledText.into())) -> Type::StyledText,
     StringToStyledText: (Type::String) -> Type::StyledText
     OpenUrl: (Type::String) -> Type::Bool,
+    BringAllToFront: () -> Type::Void,
 );
 
 impl Default for BuiltinFunctionTypes {
@@ -412,6 +414,7 @@ impl BuiltinFunction {
             BuiltinFunction::ParseMarkdown => false,
             BuiltinFunction::StringToStyledText => true,
             BuiltinFunction::OpenUrl => false,
+            BuiltinFunction::BringAllToFront => false,
         }
     }
 
@@ -497,6 +500,7 @@ impl BuiltinFunction {
             BuiltinFunction::ParseMarkdown => true,
             BuiltinFunction::StringToStyledText => true,
             BuiltinFunction::OpenUrl => false,
+            BuiltinFunction::BringAllToFront => false,
         }
     }
 }

internal/compiler/generator/cpp.rs

@@ -4926,6 +4926,9 @@ fn compile_builtin_function_call(
             let window = access_window_field(ctx);
             format!("slint::private_api::open_url({url}, {window})")
         }
+        BuiltinFunction::BringAllToFront => {
+            "slint::private_api::bring_all_to_front()".to_owned()
+        }
         BuiltinFunction::ParseMarkdown => {
             let format_string = a.next().unwrap();
             let args = a.next().unwrap();

internal/compiler/generator/rust.rs

@@ -4142,6 +4142,9 @@ fn compile_builtin_function_call(
             let window_adapter_tokens = access_window_adapter_field(ctx);
             quote!(sp::open_url(&#url, #window_adapter_tokens.window()).is_ok())
         }
+        BuiltinFunction::BringAllToFront => {
+            quote!(sp::bring_all_to_front())
+        }
         BuiltinFunction::ParseMarkdown => {
             let format_string = a.next().unwrap();
             let args = a.next().unwrap();

internal/compiler/llr/optim_passes/inline_expressions.rs

@@ -167,6 +167,7 @@ fn builtin_function_cost(function: &BuiltinFunction) -> isize {
         BuiltinFunction::ParseMarkdown => isize::MAX,
         BuiltinFunction::StringToStyledText => ALLOC_COST,
         BuiltinFunction::OpenUrl => isize::MAX,
+        BuiltinFunction::BringAllToFront => isize::MAX,
     }
 }
 

internal/compiler/passes/lower_platform.rs

@@ -34,6 +34,12 @@ pub fn lower_platform(component: &Rc<Component>, type_loader: &mut crate::typelo
             {
                 *function = BuiltinFunction::OpenUrl.into();
             }
+            Expression::FunctionCall { function, .. }
+                if matches!(&*function, Callable::Function(nr)
+                    if is_platform(nr) && nr.name() == "bring-all-to-front") =>
+            {
+                *function = BuiltinFunction::BringAllToFront.into();
+            }
             _ => {}
         })
     })

internal/core/lib.rs

@@ -175,3 +175,14 @@ pub fn is_apple_platform() -> bool {
 pub fn open_url(url: &str, window: &crate::api::Window) -> Result<(), crate::api::PlatformError> {
     crate::window::WindowInner::from_pub(window).context().platform().open_url(url)
 }
+
+#[cfg(target_os = "macos")]
+pub fn bring_all_to_front() {
+    use objc2::MainThreadMarker;
+    use objc2_app_kit::NSApplication;
+    let Some(mtm) = MainThreadMarker::new() else { return };
+    NSApplication::sharedApplication(mtm).arrangeInFront(None);
+}
+
+#[cfg(not(target_os = "macos"))]
+pub fn bring_all_to_front() {}