Layout::bottom_up -> ui.horizontal -> ui.button with style.spacing.button_padding increases size downward

[lunixbochs]

(egui 0.18.1 on macOS 12.x with winit + wgpu backend)

When you nest these elements, then increase the vertical padding in style.spacing.button_padding, the button grows downward rather than upward, which causes a few problems.

ui.with_layout(egui::Layout::bottom_up(egui::Align::Center))
  ui.horizontal()
    ui.button()

I'm using a bottom-up layout because I'm trying to put multiple buttons horizontally at the bottom of a fixed size window below the content. The buttons do appear there, but if I add button_padding, the button expands downward to grow the window rather than upward with the layout.

I had to use .fixed_size for this demonstration, because if I use e.g. .default_size, the window becomes infinitely tall (presumably no matter how big the window is, the button grows it vertically every frame)

egui::Window::new("test")
    .fixed_size((160., 160.))
    .show(ctx, |ui| {
        ui.with_layout(egui::Layout::bottom_up(egui::Align::Center), |ui| {
            ui.horizontal(|ui| {
                ui.button("bottom button");
            }); 
        }); 
    }); 

egui::Window::new("test 2")
    .fixed_size((160., 160.))
    .show(ctx, |ui| {
        ui.style_mut().spacing.button_padding = (16.0, 64.0).into();
        ui.with_layout(egui::Layout::bottom_up(egui::Align::Center), |ui| {
            ui.horizontal(|ui| {
                ui.button("bottom button");
            }); 
        }); 
    }); 

[lunixbochs]

Being more explicit about the layout seems to have helped, using a left_to_right().with_cross_align(Max) behaved about as I wanted.

egui::Window::new("test")
    .vscroll(false)
    .fixed_size((160., 160.))
    .show(ctx, |ui| {
        ui.with_layout(egui::Layout::bottom_up(egui::Align::Center), |ui| {
            ui.with_layout(egui::Layout::left_to_right().with_cross_align(egui::Align::Max), |ui| {
                ui.button("bottom button");
            }); 
        }); 
    }); 

egui::Window::new("test 2")
    .vscroll(false)
    .fixed_size((160., 160.))
    .show(ctx, |ui| {
        ui.style_mut().spacing.button_padding = (16.0, 20.0).into();
        ui.with_layout(egui::Layout::bottom_up(egui::Align::Center), |ui| {
            ui.with_layout(egui::Layout::left_to_right().with_cross_align(egui::Align::Max), |ui| {
                ui.button("bottom button");
            }); 
        }); 
    }); 

Is my issue then due the the assumed initial_size in ui.horizontal()?
Can ui.horizontal() be adapted to behave a bit better with bottom-up layout?

[emilk]

This is one of those "difficult to do in immediate mode" things. I think I'll close this in favor of #pass