RE: Limitation of Customization
I think you are right Guillaume, i'm not aware of any such document. There are, of course, lots of resources that detail what you CAN change, but I doubt there is a consolidated list of what you CANT change, I suppose that could be an endless list.
To respond to the specific examples Nimishag gave, calendar controls can be customised in as much as they have properties that can be update to determine what information they show, and the colour of the item within a calendar, but in terms of changing the "look and feel" of a calendar control, then I don't think this is possible through standard (supported) means. With forms , you can of course very much change things like the positioning of your fields, label widths etc. However, as far as I am aware you cant change the style of text boxes (such as giving them borders with rounded corners or giving them a background colour)
