Fix manual `Popup` not closing (#7383)

Fixes manually created popups (via `Popup::new`) not closing, since
widget_clicked_elsewhere was always false.

This example would never close:

```rs
    let mut open = true;

    eframe::run_simple_native("My egui App", options, move |ctx, _frame| {
        egui::CentralPanel::default().show(ctx, |ui| {
            let response = egui::Popup::new(
                Id::new("popup"),
                ctx.clone(),
                PopupAnchor::Position(Pos2::new(10.0, 10.0)),
                LayerId::new(Order::Foreground, Id::new("popup")),
            )
            .open(open)
            .show(|ui| {
                ui.label("This is a popup!");
                ui.label("You can put anything in here.");
            });

            if let Some(response) = response {
                if response.response.should_close() {
                    open = false;
                }
            }
        });
    })
```

I also noticed that the Color submenu in the popups example had a double
arrow (must have been broken in the atoms PR):

<img width="248" height="110" alt="Screenshot 2025-08-07 at 13 42 28"
src="https://github.com/user-attachments/assets/a4e0c267-ae71-4b2c-a1f0-f53f9662d026"
/>

Also fixed this in the PR.

crates/egui/src/containers/popup.rs

@@ -179,9 +179,6 @@ pub struct Popup<'a> {
     /// Gap between the anchor and the popup
     gap: f32,
 
-    /// Used later depending on close behavior
-    widget_clicked_elsewhere: bool,
-
     /// Default width passed to the Area
     width: Option<f32>,
     sense: Sense,
@@ -205,7 +202,6 @@ impl<'a> Popup<'a> {
             rect_align: RectAlign::BOTTOM_START,
             alternative_aligns: None,
             gap: 0.0,
-            widget_clicked_elsewhere: false,
             width: None,
             sense: Sense::click(),
             layout: Layout::default(),
@@ -219,14 +215,12 @@ impl<'a> Popup<'a> {
     ///
     /// See [`Self::menu`] and [`Self::context_menu`] for common use cases.
     pub fn from_response(response: &Response) -> Self {
-        let mut popup = Self::new(
+        Self::new(
             Self::default_response_id(response),
             response.ctx.clone(),
             response,
             response.layer_id,
-        );
-        popup.widget_clicked_elsewhere = response.clicked_elsewhere();
-        popup
+        )
     }
 
     /// Show a popup relative to some widget,
@@ -504,9 +498,14 @@ impl<'a> Popup<'a> {
     /// Returns `None` if the popup is not open or anchor is `PopupAnchor::Pointer` and there is
     /// no pointer.
     pub fn show<R>(self, content: impl FnOnce(&mut Ui) -> R) -> Option<InnerResponse<R>> {
-        let hover_pos = self.ctx.pointer_hover_pos();
-
         let id = self.id;
+        // When the popup was just opened with a click we don't want to immediately close it based
+        // on the `PopupCloseBehavior`, so we need to remember if the popup was already open on
+        // last frame. A convenient way to check this is to see if we have a response for the `Area`
+        // from last frame:
+        let was_open_last_frame = self.ctx.read_response(id).is_some();
+
+        let hover_pos = self.ctx.pointer_hover_pos();
         if let OpenKind::Memory { set } = self.open_kind {
             match set {
                 Some(SetOpenCommand::Bool(open)) => {
@@ -548,7 +547,6 @@ impl<'a> Popup<'a> {
             rect_align: _,
             alternative_aligns: _,
             gap,
-            widget_clicked_elsewhere,
             width,
             sense,
             layout,
@@ -595,10 +593,13 @@ impl<'a> Popup<'a> {
             frame.show(ui, content).inner
         });
 
+        // If the popup was just opened with a click, we don't want to immediately close it again.
+        let close_click = was_open_last_frame && ctx.input(|i| i.pointer.any_click());
+
         let closed_by_click = match close_behavior {
-            PopupCloseBehavior::CloseOnClick => widget_clicked_elsewhere,
+            PopupCloseBehavior::CloseOnClick => close_click,
             PopupCloseBehavior::CloseOnClickOutside => {
-                widget_clicked_elsewhere && response.response.clicked_elsewhere()
+                close_click && response.response.clicked_elsewhere()
             }
             PopupCloseBehavior::IgnoreClicks => false,
         };

crates/egui_demo_lib/src/demo/popups.rs

@@ -2,8 +2,8 @@ use crate::rust_view_ui;
 use egui::color_picker::{Alpha, color_picker_color32};
 use egui::containers::menu::{MenuConfig, SubMenuButton};
 use egui::{
-    Align, Align2, ComboBox, Frame, Id, Layout, Popup, PopupCloseBehavior, RectAlign, RichText,
-    Tooltip, Ui, UiBuilder, include_image,
+    Align, Align2, Atom, Button, ComboBox, Frame, Id, Layout, Popup, PopupCloseBehavior, RectAlign,
+    RichText, Tooltip, Ui, UiBuilder, include_image,
 };
 
 /// Showcase [`Popup`].
@@ -79,13 +79,15 @@ impl PopupsDemo {
                 } else {
                     egui::Color32::WHITE
                 };
-                let mut color_button =
-                    SubMenuButton::new(RichText::new("Background").color(text_color));
-                color_button.button = color_button.button.fill(self.color);
-                color_button.button = color_button
-                    .button
-                    .right_text(RichText::new(SubMenuButton::RIGHT_ARROW).color(text_color));
-                color_button.ui(ui, |ui| {
+
+                let button = Button::new((
+                    RichText::new("Background").color(text_color),
+                    Atom::grow(),
+                    RichText::new(SubMenuButton::RIGHT_ARROW).color(text_color),
+                ))
+                .fill(self.color);
+
+                SubMenuButton::from_button(button).ui(ui, |ui| {
                     ui.spacing_mut().slider_width = 200.0;
                     color_picker_color32(ui, &mut self.color, Alpha::Opaque);
                 });