src/vs/base/browser/ui/splitview/splitview.ts/SplitView/relayout
class SplitView:	private relayout(lowPriorityIndexes?: number[], highPriorityIndexes?: number[]): void {
		const contentSize = this.viewItems.reduce((r, i) => r + i.size, 0);

		this.resize(this.viewItems.length - 1, this.size - contentSize, undefined, lowPriorityIndexes, highPriorityIndexes);
		this.distributeEmptySpace();
		this.layoutViews();
		this.saveProportions();
	}