Fix: increase the size of button_padding.y in ui.horizontal(), the widgets will create a step layer.

[rustbasic]

This commit is an example showing that issue is solved.

• Related Fix: Positioning issues with Slider and other Button. #4937

• Related Improvement: Apply button_padding and drag_value_text_style applied in Slider., #5027

• Closes increase the size of button_padding.y in ui.horizontal(), the widgets will create a step layer. #5029

Dear emilk.

This commit is an example showing that issue is solved.
This way, issues are resolved and it is difficult to find new and strange places.
I don't know what effect it has on Grid or Layout::Center etc.
I didn't check if allocate_new_ui() handles this.

In Button : allocate_at_least() -> allocate_response() -> allocate_space() -> allocate_space_impl() -> placer.justify_and_align().

In Horizontal : horizontal() -> horizontal_with_main_wrap_dyn() -> allocate_ui_with_layout_dyn() -> placer.justify_and_align()

looks like justify_and_align() is being called twice.