How to modify the small icon on the left side of CollapsingState

[KUKU-zero2]

As the title suggests, the small icon of CollapsingState matches the background color. How can I change it? Thank you

[YgorSouza]

Use show_toggle_button instead of show_header. There is an example there in the docs, but if you also want it to toggle when you click on the name, like the default header, you also have to call the toggle method that isn't mentioned in the example:

            let header_res = ui.horizontal(|ui| {
                if ui.label("Header").clicked() {
                    state.toggle(ui);
                }
                state.show_toggle_button(ui, circle_icon);
            });

[KUKU-zero2]

使用show_toggle_button代替show_header。文档中有一个示例，但如果您还希望在单击名称时切换它（如默认标题），您还必须调用toggle示例中未提及的方法：

            let header_res = ui.horizontal(|ui| {
                if ui.label("Header").clicked() {
                    state.toggle(ui);
                }
                state.show_toggle_button(ui, circle_icon);
            });

Thank you for your answer. This is indeed a good method, and writing it as a trait is very useful.