src/vs/editor/browser/controller/mouseTarget.ts/MouseTargetFactory/_getMouseColumn
class MouseTargetFactory:	public static _getMouseColumn(mouseContentHorizontalOffset: number, typicalHalfwidthCharacterWidth: number): number {
		if (mouseContentHorizontalOffset < 0) {
			return 1;
		}
		const chars = Math.round(mouseContentHorizontalOffset / typicalHalfwidthCharacterWidth);
		return (chars + 1);
	}