expander

pub fn expander(self: *Branch, src: std.builtin.SourceLocation, init_opts: ExpanderOptions, opts: Options) bool {
        var clicked: bool = false;
        if (self.button.clicked()) {
            clicked = true;
        }

        self.hbox.deinit();
        self.button.deinit();

        const default_opts = Options{
            .name = "Expander",
            .margin = .{ .x = init_opts.indent },
        };

        self.anim = dvui.animate(
            @src(),
            .{
                .duration = self.init_options.animation_duration,
                .easing = self.init_options.animation_easing,
                .kind = if (self.init_options.animation_duration > 0) .vertical else .none,
            },
            default_opts.override(opts),
        );

        if (clicked) {
            if (self.expanded) {
                self.anim.?.init_opts.easing = dvui.easing.outQuad;
                self.anim.?.init_opts.duration = @divTrunc(self.init_options.animation_duration, 2);
                self.anim.?.startEnd();
            } else {
                self.anim.?.val = 0.0;
                self.anim.?.start();
                self.expanded = true;
            }
        }

        if (self.anim.?.end()) {
            self.expanded = false;
        }

        if (self.expanded) {
            // Always expand the inner box to fill the animation
            const expander_opts = dvui.Options{ .expand = .both };

            self.expander_vbox.init(src, .{ .dir = .vertical }, expander_opts.override(opts.strip()));
            self.expander_vbox.drawBackground();
        }

        self.can_expand = true;

        return self.expanded;
    }