A number of fixes relating to how CPSplitView divides itself by default, as well as adding CPView-viewWillDraw.

Reviewed by Tom.

AppKit/CPView.j

@@ -1435,6 +1435,8 @@ setBoundsOrigin:
 */
 - (void)displayRect:(CPRect)aRect
 {
+    [self viewWillDraw];
+    
     [self displayRectIgnoringOpacity:aRect inContext:nil];
     
     _dirtyRect = NULL;
@@ -1450,6 +1452,10 @@ setBoundsOrigin:
     [self unlockFocus];
 }
 
+- (void)viewWillDraw
+{
+}
+
 /*
     Locks focus on the receiver, so drawing commands apply to it.
 */