Modals: Add `UiKind::Modal`, and consume escape-key properly (#5414)

Small fixes/improvements to `Modal`

- Fixes #5413

crates/egui/src/containers/modal.rs

@@ -1,5 +1,5 @@
 use crate::{
-    Area, Color32, Context, Frame, Id, InnerResponse, Order, Response, Sense, Ui, UiBuilder,
+    Area, Color32, Context, Frame, Id, InnerResponse, Order, Response, Sense, Ui, UiBuilder, UiKind,
 };
 use emath::{Align2, Vec2};
 
@@ -32,6 +32,7 @@ impl Modal {
     /// - order: foreground
     pub fn default_area(id: Id) -> Area {
         Area::new(id)
+            .kind(UiKind::Modal)
             .sense(Sense::hover())
             .anchor(Align2::CENTER_CENTER, Vec2::ZERO)
             .order(Order::Foreground)
@@ -153,8 +154,12 @@ impl<T> ModalResponse<T> {
     ///  - this is the topmost modal, no popup is open and the escape key was pressed
     pub fn should_close(&self) -> bool {
         let ctx = &self.response.ctx;
-        let escape_clicked = ctx.input(|i| i.key_pressed(crate::Key::Escape));
+
+        // this is a closure so that `Esc` is consumed only if the modal is topmost
+        let escape_clicked =
+            || ctx.input_mut(|i| i.consume_key(crate::Modifiers::NONE, crate::Key::Escape));
+
         self.backdrop_response.clicked()
-            || (self.is_top_modal && !self.any_popup_open && escape_clicked)
+            || (self.is_top_modal && !self.any_popup_open && escape_clicked())
     }
 }

crates/egui/src/ui_stack.rs

@@ -24,6 +24,9 @@ pub enum UiKind {
     /// A bottom [`crate::TopBottomPanel`].
     BottomPanel,
 
+    /// A modal [`crate::Modal`].
+    Modal,
+
     /// A [`crate::Frame`].
     Frame,
 
@@ -82,6 +85,7 @@ impl UiKind {
 
             Self::Window
             | Self::Menu
+            | Self::Modal
             | Self::Popup
             | Self::Tooltip
             | Self::Picker
@@ -228,6 +232,12 @@ impl UiStack {
         self.kind().map_or(false, |kind| kind.is_panel())
     }
 
+    /// Is this [`crate::Ui`] an [`crate::Area`]?
+    #[inline]
+    pub fn is_area_ui(&self) -> bool {
+        self.kind().map_or(false, |kind| kind.is_area())
+    }
+
     /// Is this a root [`crate::Ui`], i.e. created with [`crate::Ui::new()`]?
     #[inline]
     pub fn is_root_ui(&self) -> bool {