src/vs/base/browser/ui/splitview/splitview.ts/SplitView/onViewChange
class SplitView:	private onViewChange(item: ViewItem<TLayoutContext>, size: number | undefined): void {
		const index = this.viewItems.indexOf(item);

		if (index < 0 || index >= this.viewItems.length) {
			return;
		}

		size = typeof size === 'number' ? size : item.size;
		size = clamp(size, item.minimumSize, item.maximumSize);

		if (this.inverseAltBehavior && index > 0) {
			// In this case, we want the view to grow or shrink both sides equally
			// so we just resize the "left" side by half and let `resize` do the clamping magic
			this.resize(index - 1, Math.floor((item.size - size) / 2));
			this.distributeEmptySpace();
			this.layoutViews();
		} else {
			item.size = size;
			this.relayout([index], undefined);
		}
	}