/*
	Copyright 2011 Philip Dow / Sprouted. All rights reserved.
*/

/*

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	materials provided with the distribution.

	* Neither the name of the author nor the names of its contributors may be used to 
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	THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS “AS IS” AND ANY 
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*/

/*
	For non-attribution licensing options refer to http://phildow.net/licensing/
*/


/*
	SPTextAndHeaderView is a custom view subclass meant to be used as the document view
	of a scroll view. It allows you to lay out a header view alongside a text view inside
	a single NSScrollView.
	
	Scroll views manage single document subviews, for example, a single text view. As the
	text view changes its geometry because of user input, the scroll view adjusts its clip 
	view to encompass the visible area.
	
	There has been a need to lay out additional views alongside the text view while keeping 
	everything within the text view's enclosing scroll view. Scrolling can then encompass
	all the views, so that with a vertical scroll a header view will eventually disappear,
	falling outside the scroll view's clipping area. Apple's Mail program exhibits this 
	behavior when reading messages. Normally, scrolling would only scroll the text, keeping 
	the header view visible. This behavior is not always desirable.
	
	SPTextAndHeaderView coordinates between a header view, which itself can contain any kind
	and number of subviews, a text view, and an enclosing scroll view. The header view is
	kept in place at the top, while changes to the text view's geometry are mediated to the 
	enclosing scroll view. The class remains compatibility with the system's ruler APIs.
*/