diff --git a/crates/egui/src/atomics/atom_widget.rs b/crates/egui/src/atomics/atom_widget.rs
index 3fa56a12f..125ba03e0 100644
--- a/crates/egui/src/atomics/atom_widget.rs
+++ b/crates/egui/src/atomics/atom_widget.rs
@@ -1,9 +1,11 @@
 use crate::{
-    Atom, AtomExt as _, AtomKind, AtomLayout, Atoms, Button, Context, Id, InnerResponse, IntoAtoms,
-    Layout, Response, Sense, Spacing, Style, Ui, UiBuilder, Visuals, WidgetRect,
+    Atom, AtomExt as _, AtomKind, AtomLayout, Atoms, Button, ClosableTag, Context, Id,
+    InnerResponse, IntoAtoms, LayerId, Layout, Response, Sense, Spacing, Style, Ui, UiBuilder,
+    UiStack, Visuals, WidgetRect,
 };
 use emath::{Align, Pos2, Rect, Vec2};
 use epaint::Direction;
+use std::sync::Arc;
 
 pub fn atom() -> Atom<'static> {
     Atom::default()
@@ -62,6 +64,22 @@ macro_rules! impl_widget_for_atom_widget {
 
 pub trait IsAtomWidgetContext {
     fn ctx(&self) -> &crate::Context;
+
+    /// Where we are in the [`UiStack`].
+    ///
+    /// Widgets built from atoms don't need this, but things that also open a container do:
+    /// [`crate::SubMenuButton`] needs it to find the menu it sits in.
+    fn stack(&self) -> &Arc<UiStack>;
+
+    /// The [`LayerId`] the widgets are drawn on.
+    fn layer_id(&self) -> LayerId;
+
+    /// The [`Id`] the next widget will get, without claiming it.
+    ///
+    /// Use this when a widget's state has to be read before the widget is added, like
+    /// [`crate::SubMenuButton`] reading whether its submenu is open.
+    fn next_auto_id(&self) -> Id;
+
     fn make_auto_id(&mut self) -> Id;
 
     fn is_enabled(&self) -> bool;
@@ -86,6 +104,36 @@ pub trait IsAtomWidgetContext {
     fn read_response(&self, id: Id) -> Response;
 
     fn child_ui(&mut self, builder: UiBuilder) -> Ui;
+
+    /// Close the closest closable container, e.g. the menu we are in.
+    ///
+    /// See [`Ui::close`].
+    fn close(&self) {
+        let tag = self.stack().iter().find_map(|stack| {
+            stack
+                .info
+                .tags
+                .get_downcast::<ClosableTag>(ClosableTag::NAME)
+        });
+        if let Some(tag) = tag {
+            tag.set_close();
+        } else {
+            log::warn!("Called close() on something that has no closable parent.");
+        }
+    }
+
+    /// Will any closable container we are in close this frame?
+    ///
+    /// See [`Ui::will_parent_close`].
+    fn will_parent_close(&self) -> bool {
+        self.stack().iter().any(|stack| {
+            stack
+                .info
+                .tags
+                .get_downcast::<ClosableTag>(ClosableTag::NAME)
+                .is_some_and(|tag| tag.should_close())
+        })
+    }
 }
 
 pub type AtomWidgetContext = dyn IsAtomWidgetContext;
@@ -95,8 +143,20 @@ impl IsAtomWidgetContext for Ui {
         self.ctx()
     }
 
+    fn stack(&self) -> &Arc<UiStack> {
+        self.stack()
+    }
+
+    fn layer_id(&self) -> LayerId {
+        self.layer_id()
+    }
+
+    fn next_auto_id(&self) -> Id {
+        self.next_auto_id()
+    }
+
     fn make_auto_id(&mut self) -> Id {
-        let id = self.next_auto_id();
+        let id = IsAtomWidgetContext::next_auto_id(self);
         self.skip_ahead_auto_ids(1);
         id
     }
@@ -133,6 +193,18 @@ impl<'ui, 'layout> AtomUi<'ui, 'layout> {
         Self { ctx, layout }
     }
 
+    /// The context the widgets are built in.
+    ///
+    /// Needed by things that also open a container, like [`crate::SubMenuButton`].
+    pub fn context(&self) -> &AtomWidgetContext {
+        self.ctx
+    }
+
+    /// The [`Id`] the next widget added here will get, without claiming it.
+    pub fn next_auto_id(&self) -> Id {
+        self.ctx.next_auto_id()
+    }
+
     /// The [`Style`] the widgets built here will use.
     pub fn style(&self) -> &Style {
         self.ctx.style()
@@ -311,3 +383,40 @@ fn read_or_default_response(ui: &Ui, id: Id, sense: Sense) -> Response {
         })
     })
 }
+
+pub trait AnyUi<'a> {
+    fn add(&mut self, w: impl AtomWidget<'a>) -> Response;
+
+    fn style(&self) -> &Style;
+
+    fn style_mut(&mut self) -> &mut Style;
+}
+
+impl<'a> AnyUi<'a> for AtomUi<'_, 'a> {
+    fn add(&mut self, w: impl AtomWidget<'a>) -> Response {
+        self.add(atom(), w)
+    }
+
+    fn style(&self) -> &Style {
+        self.style()
+    }
+
+    fn style_mut(&mut self) -> &mut Style {
+        self.style_mut()
+    }
+}
+
+impl<'a> AnyUi<'a> for Ui {
+    fn add(&mut self, w: impl AtomWidget<'a>) -> Response {
+        let layout = w.show_for(self).0;
+        self.add(layout)
+    }
+
+    fn style(&self) -> &Style {
+        self.style()
+    }
+
+    fn style_mut(&mut self) -> &mut Style {
+        self.style_mut()
+    }
+}
diff --git a/crates/egui/src/containers/area.rs b/crates/egui/src/containers/area.rs
index cdc5c7ec8..f10dc46a4 100644
--- a/crates/egui/src/containers/area.rs
+++ b/crates/egui/src/containers/area.rs
@@ -658,7 +658,13 @@ impl Area {
         let sized = layout.measure(&content_ui, prepared.available_size);
         let size = sized.outer_size;
         prepared.resize(ctx, size);
-        sized.show_at(&content_ui, prepared.state.rect());
+        let rect = prepared.state.rect();
+
+        // Atoms are painted, not allocated, so the `Ui` never learns where it ended up.
+        // Tell it, so `Ui::response` is right for whoever reads it (menus do).
+        content_ui.force_set_min_rect(rect);
+
+        sized.show_at(&content_ui, rect);
 
         let response = prepared.end_with_size(ctx, content_ui, size);
         InnerResponse { inner, response }
diff --git a/crates/egui/src/containers/menu.rs b/crates/egui/src/containers/menu.rs
index d4c95b298..d050ddf5f 100644
--- a/crates/egui/src/containers/menu.rs
+++ b/crates/egui/src/containers/menu.rs
@@ -10,8 +10,9 @@
 
 use crate::style::StyleModifier;
 use crate::{
-    Button, Color32, Context, Frame, Id, InnerResponse, IntoAtoms, Layout, PointerButton, Popup,
-    PopupCloseBehavior, Response, Style, Ui, UiBuilder, UiKind, UiStack, UiStackInfo, Widget as _,
+    AnyUi, Atom, AtomUi, AtomWidgetContext, Button, Color32, Context, Frame, Id, InnerResponse,
+    IntoAtoms, Layout, PointerButton, Popup, PopupCloseBehavior, Response, Style, Ui, UiBuilder,
+    UiKind, UiStack, UiStackInfo, Widget as _,
 };
 use emath::{Align, RectAlign, Vec2, vec2};
 use epaint::Stroke;
@@ -30,7 +31,12 @@ pub fn menu_style(style: &mut Style) {
 
 /// Find the root [`UiStack`] of the menu.
 pub fn find_menu_root(ui: &Ui) -> &UiStack {
-    ui.stack()
+    find_menu_root_in_stack(ui.stack())
+}
+
+/// Find the root [`UiStack`] of the menu, starting from `stack`.
+pub fn find_menu_root_in_stack(stack: &UiStack) -> &UiStack {
+    stack
         .iter()
         .find(|stack| {
             stack.is_root_ui()
@@ -144,8 +150,17 @@ impl MenuState {
 
     /// Find the root of the menu and get the state
     pub fn from_ui<R>(ui: &Ui, f: impl FnOnce(&mut Self, &UiStack) -> R) -> R {
-        let stack = find_menu_root(ui);
-        Self::from_id(ui.ctx(), stack.id, |state| f(state, stack))
+        Self::from_stack(ui.ctx(), ui.stack(), f)
+    }
+
+    /// Find the root of the menu and get the state, from a [`UiStack`].
+    pub fn from_stack<R>(
+        ctx: &Context,
+        stack: &UiStack,
+        f: impl FnOnce(&mut Self, &UiStack) -> R,
+    ) -> R {
+        let root = find_menu_root_in_stack(stack);
+        Self::from_id(ctx, root.id, |state| f(state, root))
     }
 
     /// Get the state via the menus root [`Ui`] id
@@ -373,22 +388,62 @@ impl<'a> SubMenuButton<'a> {
         ui: &mut Ui,
         content: impl FnOnce(&mut Ui) -> R,
     ) -> (Response, Option<InnerResponse<R>>) {
-        let my_id = ui.next_auto_id();
-        let open = MenuState::from_ui(ui, |state, _| {
-            state.open_item == Some(SubMenu::id_from_widget_id(my_id))
-        });
-        let inactive = ui.style().visuals.widgets.inactive;
-        // TODO(lucasmerlin) add `open` function to `Button`
-        if open {
-            ui.style_mut().visuals.widgets.inactive = ui.style().visuals.widgets.open;
-        }
-        let response = self.button.ui(ui);
-        ui.style_mut().visuals.widgets.inactive = inactive;
+        let Self { button, sub_menu } = self;
 
-        let popup_response = self.sub_menu.show(ui, &response, content);
+        let open = is_sub_menu_open(ui, ui.next_auto_id());
+        let response = with_open_style(ui, open, |ui| button.ui(ui));
+
+        let popup_response = sub_menu.show(ui, &response, content);
 
         (response, popup_response)
     }
+
+    /// Show the submenu button in an [`AtomUi`], with [`crate::Atom`]-based submenu contents.
+    ///
+    /// Like [`Self::ui`], but both the button and the submenu are built from atoms, so the
+    /// submenu needs no sizing pass. See [`Popup::show_atom`].
+    pub fn atom_ui<'l, R>(
+        self,
+        ui: &mut AtomUi<'_, 'l>,
+        content: impl FnOnce(&mut AtomUi<'_, 'l>) -> R,
+    ) -> (Response, Option<InnerResponse<R>>)
+    where
+        'a: 'l,
+    {
+        let Self { button, sub_menu } = self;
+
+        let open = is_sub_menu_open(ui.context(), ui.next_auto_id());
+        let response = with_open_style(ui, open, |ui| ui.add(Atom::default(), button));
+
+        let popup_response = sub_menu.show_atom(ui.context(), &response, content);
+
+        (response, popup_response)
+    }
+}
+
+/// Is the submenu belonging to the widget with this id open?
+fn is_sub_menu_open(ui: &AtomWidgetContext, widget_id: Id) -> bool {
+    MenuState::from_stack(ui.ctx(), ui.stack(), |state, _| {
+        state.open_item == Some(SubMenu::id_from_widget_id(widget_id))
+    })
+}
+
+/// Run `add_button` with the `open` widget visuals in place of the inactive ones, so an open
+/// submenu's button looks open.
+// TODO(lucasmerlin) add `open` function to `Button`
+fn with_open_style<'a, UI: AnyUi<'a>, R>(
+    ui: &mut UI,
+    open: bool,
+    add_button: impl FnOnce(&mut UI) -> R,
+) -> R {
+    if !open {
+        return add_button(ui);
+    }
+    let inactive = ui.style().visuals.widgets.inactive;
+    ui.style_mut().visuals.widgets.inactive = ui.style().visuals.widgets.open;
+    let response = add_button(ui);
+    ui.style_mut().visuals.widgets.inactive = inactive;
+    response
 }
 
 /// Show a submenu in a menu.
@@ -428,15 +483,51 @@ impl SubMenu {
         ui: &Ui,
         button_response: &Response,
         content: impl FnOnce(&mut Ui) -> R,
+    ) -> Option<InnerResponse<R>> {
+        self.show_impl(ui, button_response, |popup| {
+            popup.show(|ui| {
+                keep_menu_on_top(ui, button_response);
+                content(ui)
+            })
+        })
+    }
+
+    /// Show the submenu, with [`crate::Atom`]-based contents.
+    ///
+    /// Like [`Self::show`], but the submenu is measured before it is painted, so it is
+    /// correctly sized and placed on the frame it opens. See [`Popup::show_atom`].
+    pub fn show_atom<'l, R>(
+        self,
+        ui: &AtomWidgetContext,
+        button_response: &Response,
+        content: impl FnOnce(&mut AtomUi<'_, 'l>) -> R,
+    ) -> Option<InnerResponse<R>> {
+        self.show_impl(ui, button_response, |popup| {
+            popup.show_atom(|atom_ui| {
+                keep_menu_on_top(atom_ui.context(), button_response);
+                content(atom_ui)
+            })
+        })
+    }
+
+    /// Everything [`Self::show`] and [`Self::show_atom`] have in common: deciding whether the
+    /// submenu should be open, configuring the [`Popup`], and handling the close behavior.
+    /// `show_popup` shows the contents.
+    fn show_impl<R>(
+        self,
+        ui: &AtomWidgetContext,
+        button_response: &Response,
+        show_popup: impl FnOnce(Popup<'_>) -> Option<InnerResponse<R>>,
     ) -> Option<InnerResponse<R>> {
         let frame = Frame::menu(ui.style());
 
         let id = Self::id_from_widget_id(button_response.id);
 
         // Get the state from the parent menu
-        let (open_item, menu_id, parent_config) = MenuState::from_ui(ui, |state, stack| {
-            (state.open_item, stack.id, MenuConfig::from_stack(stack))
-        });
+        let (open_item, menu_id, parent_config) =
+            MenuState::from_stack(ui.ctx(), ui.stack(), |state, stack| {
+                (state.open_item, stack.id, MenuConfig::from_stack(stack))
+            });
 
         let mut menu_config = self.config.unwrap_or_else(|| parent_config.clone());
         menu_config.bar = false;
@@ -499,7 +590,7 @@ impl SubMenu {
         let expand = Vec2::new(0.0, frame.total_margin().sum().y / 2.0);
         response.interact_rect = response.interact_rect.expand2(expand);
 
-        let popup_response = Popup::from_response(&response)
+        let popup = Popup::from_response(&response)
             .id(id)
             .open(is_open)
             .align(RectAlign::RIGHT_START)
@@ -512,14 +603,9 @@ impl SubMenu {
             .info(
                 UiStackInfo::new(UiKind::Menu)
                     .with_tag_value(MenuConfig::MENU_CONFIG_TAG, menu_config.clone()),
-            )
-            .show(|ui| {
-                // Ensure our layer stays on top when the button is clicked
-                if button_response.clicked() || button_response.is_pointer_button_down_on() {
-                    ui.ctx().move_to_top(ui.layer_id());
-                }
-                content(ui)
-            });
+            );
+
+        let popup_response = show_popup(popup);
 
         if let Some(popup_response) = &popup_response {
             // If no child sub menu is open means we must be the deepest child sub menu.
@@ -556,14 +642,14 @@ impl SubMenu {
                 ui.close();
             }
 
-            let is_moving_towards_rect = ui.input(|i| {
+            let is_moving_towards_rect = ui.ctx().input(|i| {
                 i.pointer
                     .is_moving_towards_rect(&popup_response.response.rect)
             });
             if is_moving_towards_rect {
                 // We need to repaint while this is true, so we can detect when
                 // the pointer is no longer moving towards the rect
-                ui.request_repaint();
+                ui.ctx().request_repaint();
             }
             let hovering_other_menu_entry = is_open
                 && !is_hovered
@@ -583,7 +669,7 @@ impl SubMenu {
             }
 
             if ui.will_parent_close() {
-                ui.data_mut(|data| data.remove_by_type::<MenuState>());
+                ui.ctx().data_mut(|data| data.remove_by_type::<MenuState>());
             }
         }
 
@@ -596,3 +682,10 @@ impl SubMenu {
         popup_response
     }
 }
+
+/// Ensure the submenu's layer stays on top while its button is being clicked.
+fn keep_menu_on_top(ui: &AtomWidgetContext, button_response: &Response) {
+    if button_response.clicked() || button_response.is_pointer_button_down_on() {
+        ui.ctx().move_to_top(ui.layer_id());
+    }
+}