src/vs/base/browser/ui/splitview/paneview.ts/Pane/minimumSize
class Pane:	get minimumSize(): number {
		const headerSize = this.headerSize;
		const expanded = !this.headerVisible || this.isExpanded();
		const minimumBodySize = expanded ? this.minimumBodySize : 0;

		return headerSize + minimumBodySize;
	}