on the year calender

my idea is simple when you show the yearly calender from jan to dec if say you have booked a weeks holiday the days on the yearly calender the days can be shown in say a different colour as they are only in a darker black which is quite hard to see and as there are so many uses for a yearly calender say like a landlord can keep track of his tenants coming and going three months in say blue new tenant going in say green

just a thought