src/vs/workbench/contrib/mergeEditor/browser/view/mergeEditor.ts/MergeEditor/toggleShowBaseCenter
class MergeEditor:	public toggleShowBaseCenter(): void {
		const showBaseCenter = this._layoutMode.value.showBase && !this._layoutMode.value.showBaseAtTop;
		this.setLayout({
			...this._layoutMode.value,
			showBaseAtTop: false,
			showBase: !showBaseCenter,
		});
	}