Ability to pass data / control state of context_menu

[enomado]

Current API relied on response.rect. When we want to show menu, we associate it with response, e.g. menu call context_interaction to get menu events(create, close, stay) internally. All this stuff is private and couldnt be accessed outside egui.

This behavior dont work if we want to track entity user clicked inside response.rect in our own.

When I have map, diagram, timeline - there is no way to know exact point was clicked on menu creation.

I have my own fork with workaround inside:
It is context_menu function

     let menu_response = egui::menu::MenuRoot::context_interaction(response, root, id);

added code is here. we just inject some inter-frame-object

    let my_state = match &menu_response {
        egui::menu::MenuResponse::Create(_, _) => {
            my_state.store()
        }
        _ => MyState::load()
    };
        

and pass my_state to the render function

bar_state.show(response, |ui| my_context_menu_render(ui, my_state));         

But it requires a lot of doing pub(crate) -> pub replacements.

Then I forked menu.rs, but it couldnt work because ui.set_menu_state is private as well.

1. So my naive API, just to check out the idea, may be something like:

response
.menu_clicked(|my_state, menu_response| 
    if menu_response == 'create'{ my_state = row_id}
    if menu_response == 'close'{ clean_resources() }
true
)
.show_menu(|ui, my_state| {...})

2. Much easier API would be

resp.context_menu(|ui, menu_handle|{
menu_handle. is_just_created() ?
menu_handle. some_handle_i_could_associate the data() ?
menu_handle. is_about_to_close() ?
})

Btw, looks like currently we have ui.close_menu() as this menu_handle germ.

3. Probably, simplest and most useful API would to just make ui.menu_state.response public.

so I could do

resp.context_menu(|ui|{
    if ui.menu_state.response == 'create'{
     memory.save_my_data()
    }
})

(but currently show is earlier that setting the response)

4. Make context_menu and all related stuff public to allow everybody inline it on his own function and add some logic. Current implementation is very easy to do this, except private visibility.

personally I like №4

PS: MenuResponse::Create(**pos**, id) is not enough, because map could be scrolled after menu was created. we need ability to user make his own associated data.