Aligning NSImageView so that it fills in bottom side of NSWindow

Question

I'm a total absolute NOOB in Mac Apps so be gentle ;). Read some documentations, and jumped right in. Still continue to read but I can't figure out how to align/resize the NSImageView to the NSWindow it is in (after user resize the window).

For example, this is default run state (the NSImageView is the big rect with a border at the bottom):

Then, if I resize the window, the NSImageView's height kinda stays as before, but the width kinda follows the window (but I don't know how I accomplished that). See here:

Thanks for reading. Please help.

Answer 1

I found out the solution - which is a simple AutoResizing mask.