src/vs/workbench/browser/parts/views/viewPane.ts/ViewPane/setExpanded
class ViewPane:	override setExpanded(expanded: boolean): boolean {
		const changed = super.setExpanded(expanded);
		if (changed) {
			this._onDidChangeBodyVisibility.fire(expanded);
		}
		if (this.twistiesContainer) {
			this.twistiesContainer.classList.remove(...ThemeIcon.asClassNameArray(this.getTwistyIcon(!expanded)));
			this.twistiesContainer.classList.add(...ThemeIcon.asClassNameArray(this.getTwistyIcon(expanded)));
		}
		return changed;
	}