NSCollectionViewFlowLayout collectionViewContentSize updates but the collection views frame doesn't update.

I have multiple custom NSCollectionViewFlowLayouts some of which have a vertical direction and others that have a horizontal direction.


When setting the horizontal layout the collection views frame correctly sets the height and width based on the content however when I then update the layout to the vertical layout the frame keeps the previous layouts content size.


Resizing the window manually with the mouse causes the layout to display correctly but I am unsure why this is not updating correctly programmatically. The correct size is been called from the layouts content size, in the WWDC 'what's new with NSCollectionViews' presentation you can see that this is not an issue.


The same issue can be seen in Apples 2015 WWDC what's new with NSCollectionViews sample project found at https://developer.apple.com/library/prerelease/mac/samplecode/CocoaSlideCollection/CocoaSlideCollectionUsingNSCollectionViewonOSX10.11.zip


When switching between the wrapped layout and circle layout you will see initially the height is incorrect and vise versa.


I am not sure if this is a bug, or if I am missing anything in the implementation.


Update: This looks be a OS bug, for the time been we have had to put a work around in place. Posting here so others can see the interium soloution or possibly suggest others based on the description above. (https://github.com/zenangst/Blueprints/pull/93)