Add Ui::place, to place widgets without changing the cursor

[lucasmerlin]

• Closes Cursor position goes backwards leading to overlapping widgets #7353

Currently ui.put moves the cursor after the placed widget. In my opinion that is a bit unexpected and counterproductive in most cases where ui.put makes sense.

The following example breakes with the current behavior and looks right with my change:

            ui.horizontal(|ui| {
                let custom_button_id = Id::new("custom_button");
                let response = Button::new((
                    Atom::custom(custom_button_id, Vec2::splat(18.0)),
                    "Look at my mini button!",
                ))
                .atom_ui(ui);
                if let Some(rect) = response.rect(custom_button_id) {
                    ui.put(rect, Button::new("🔎").frame_when_inactive(false));
                }

                let custom_button_id = Id::new("custom_button");
                let response = Button::new((
                    Atom::custom(custom_button_id, Vec2::splat(18.0)),
                    "Look at my mini button!",
                ))
                .atom_ui(ui);
                if let Some(rect) = response.rect(custom_button_id) {
                    ui.put(rect, Button::new("🔎").frame_when_inactive(false));
                }
            });

            ui.add_space(10.0);

            let response = ui.button("Notifications");

            ui.put(
                Rect::from_center_size(response.rect.right_top(), Vec2::splat(12.0)),
                |ui: &mut Ui| {
                    Frame::new()
                        .fill(Color32::RED)
                        .corner_radius(10.0)
                        .show(ui, |ui| {
                            ui.label(RichText::new("11").size(8.0).color(Color32::WHITE));
                        }).response
                },
            );

            ui.button("Some other button");

I had a look at reruns source code and there are no uses of ui.put that would break with this change (very little usages in general).

Alternatives

Instead of a breaking change we could of course instead introduce a new metheod (e.g. Ui::place?).

[github-actions]

Preview available at https://egui-pr-preview.github.io/pr/7359-lucasui-put-cursor
Note that it might take a couple seconds for the update to show up after the preview_build workflow has completed.

[lucasmerlin]

Change it to Ui::place and deprecate put

[lucasmerlin]

Ive now added a new Ui::place and reverted the Ui::put behaviour. I think when we initially went through this we decided to deprecate Ui::put but I think it's fine to keep it around.