src/vs/workbench/browser/parts/editor/editorPart.ts/EditorPart/arrangeGroups
class EditorPart:	arrangeGroups(arrangement: GroupsArrangement, target = this.activeGroup): void {
		if (this.count < 2) {
			return; // require at least 2 groups to show
		}

		if (!this.gridWidget) {
			return; // we have not been created yet
		}

		switch (arrangement) {
			case GroupsArrangement.EVEN:
				this.gridWidget.distributeViewSizes();
				break;
			case GroupsArrangement.MAXIMIZE:
				this.gridWidget.maximizeViewSize(target);
				break;
			case GroupsArrangement.TOGGLE:
				if (this.isGroupMaximized(target)) {
					this.arrangeGroups(GroupsArrangement.EVEN);
				} else {
					this.arrangeGroups(GroupsArrangement.MAXIMIZE);
				}

				break;
		}
	}