src/vs/editor/browser/widget/diffEditorWidget.ts/DiffEditorWidgetSideBySide/_onSashDrag
class DiffEditorWidgetSideBySide:	private _onSashDrag(e: ISashEvent): void {
		const w = this._dataSource.getWidth();
		const contentWidth = w - (this._dataSource.getOptions().renderOverviewRuler ? DiffEditorWidget.ENTIRE_DIFF_OVERVIEW_WIDTH : 0);
		const sashPosition = this.layout((this._startSashPosition! + (e.currentX - e.startX)) / contentWidth);

		this._sashRatio = sashPosition / contentWidth;

		this._dataSource.relayoutEditors();
	}