Ran into a little bug I can't find referenced here--maybe it's in Jim's list already, but I can't find it mentioned here.
I was trying to add some code to the Procedure pane of a Popup Button, and every time I put the code in and applied it, then went back to data mode to test it, the code would disappear (and consequently not function). When I would go back to graphics mode and click back on the button, it would show no code in the procedure window.
I tried it several ways, including with a simple call to a procedure (the procedure works as a menu item, by the way), and with the entire procedure in the procedure window, and both ways ended up with no function and nothing in the procedure window upon further review.
I finally put the code in the popup menu's blueprint, and it stuck and operated properly.
Version 0.1.032 (2362) on Mac OS 10.10.5.