src/vs/editor/contrib/cursorUndo/browser/cursorUndo.ts/CursorState/equals
class CursorState:	public equals(other: CursorState): boolean {
		const thisLen = this.selections.length;
		const otherLen = other.selections.length;
		if (thisLen !== otherLen) {
			return false;
		}
		for (let i = 0; i < thisLen; i++) {
			if (!this.selections[i].equalsSelection(other.selections[i])) {
				return false;
			}
		}
		return true;
	}