src/vs/editor/common/viewLayout/linesLayout.ts/LinesLayout/_changeOneWhitespace
class LinesLayout:	private _changeOneWhitespace(id: string, newAfterLineNumber: number, newHeight: number): void {
		const index = this._findWhitespaceIndex(id);
		if (index === -1) {
			return;
		}
		if (this._arr[index].height !== newHeight) {
			this._arr[index].height = newHeight;
			this._prefixSumValidIndex = Math.min(this._prefixSumValidIndex, index - 1);
		}
		if (this._arr[index].afterLineNumber !== newAfterLineNumber) {
			// `afterLineNumber` changed for this whitespace

			// Record old whitespace
			const whitespace = this._arr[index];

			// Since changing `afterLineNumber` can trigger a reordering, we're gonna remove this whitespace
			this._removeWhitespace(index);

			whitespace.afterLineNumber = newAfterLineNumber;

			// And add it again
			this._insertWhitespace(whitespace);
		}
	}