-fittingSize in all controls

[cacaodev]

@property(readonly) CPSize fittingSize;

The minimum size of the view that satisfies the constraints it holds.

AppKit sets this property to the best size available for the view, considering all of the constraints it and its subviews hold and satisfying a preference to make the view as small as possible. The size values in this property are never negative.

[cacaodev]

Note: -fitingSize is computed by cloning the engine and trying to minimize the control size.