Render marks under pointer check for slow input

egui_marks.rs

// Put this in your `update` to render marks under the cursor to tell if your input is slow

    let input_pos = ui.ctx().input(|input| input.pointer.latest_pos());
    let marks = ui.memory_mut(|mem| {
        let marks: &mut VecDeque<Pos2> =
            mem.data.get_temp_mut_or_default(Id::new("dots"));
        if let Some(pos) = input_pos {
            if pos == marks.back().cloned().unwrap_or_default() {
                // Add a small offset if position is repeated
                marks.push_back(pos + vec2(3.0, 3.0));
            } else {
                marks.push_back(pos);
            }
        } else {
            marks.push_back(pos2(50.0, 50.0));
        }
        if marks.len() > 200 {
            marks.pop_front();
        }
        marks.clone()
    });
    for mark in marks {
        painter.circle_filled(mark, 2.0, Color32::LIGHT_GREEN);
    }