combobox in a menu button isn't functional

[bananaturtlesandwich]

Describe the bug
when using a combobox in a menu button it doesn't work :/
also clicking buttons makes the dialog close normally but that's covered in #335

To Reproduce
Steps to reproduce the behavior:
compile this with eframe as a dependency (just a quick test thing i made not the use case)

fn main() -> Result<(), eframe::Error> {
    let mut list: Vec<String> = Vec::new();
    let mut index = None;
    eframe::run_simple_native("combo test", Default::default(), move |ctx, _| {
        use eframe::egui;
        egui::CentralPanel::default().show(ctx, |ui| {
            let mut show_combo = |ui: &mut egui::Ui| {
                ui.horizontal(|ui| {
                    let mut remove_at = None;
                    egui::ComboBox::from_id_source("select")
                        .width(125.0)
                        .selected_text(match index {
                            // for some reason this is necessary
                            Some(i) => &list[i] as &str,
                            None => "none",
                        })
                        .show_ui(ui, |ui| {
                            if ui.selectable_label(index.is_none(), "none").clicked() {
                                index = None;
                            }
                            for (i, pak) in list.iter().enumerate() {
                                ui.horizontal(|ui| {
                                    if ui.selectable_label(index == Some(i), pak).clicked() {
                                        index = Some(i);
                                    }
                                    if ui.button("x").clicked() {
                                        remove_at = Some(i);
                                        if index == remove_at {
                                            index = None
                                        }
                                        if index.is_some_and(|index| index > i) {
                                            index.as_mut().map(|i| *i -= 1);
                                        }
                                    }
                                });
                            }
                        });
                    if let Some(i) = remove_at {
                        list.remove(i);
                    }
                    if ui.button("+").clicked() {
                        list.push("test".to_string())
                    }
                })
            };
            show_combo(ui);
            ui.menu_button("test", show_combo);
        });
    })
}

Expected behavior
selecting something in the first combobox works fine while selecting something in the menu button combobox does nothing and the selected is the same
the same for clicking the remove button

Desktop (please complete the following information):

• OS: windows
• Version: 10