src/vs/editor/common/config/editorOptions.ts/EditorLineDecorationsWidth/validate
class EditorLineDecorationsWidth:	public validate(input: any): number {
		if (typeof input === 'string' && /^\d+(\.\d+)?ch$/.test(input)) {
			const multiple = parseFloat(input.substring(0, input.length - 2));
			return -multiple; // negative numbers signal a multiple
		} else {
			return EditorIntOption.clampedInt(input, this.defaultValue, 0, 1000);
		}
	}