One of the bigger challenges for our team in FileMaker Pro 14 & 15 is that when you double-click on a button in layout mode, the initial "Button Setup" floating window that appears no longer shows the specified script parameter on that first floating window screen (if a script is attached to that button). You now have to go to the NEXT screen in order to see the script parameter.
We use script parameters all the time, and in FileMaker Pro 13 and earlier, it was very quick & convenient to see what script parameter was attached to a button's script... we just double-clicked on the button to check and/or change its script parameter.
But now, we have to go through the extra step of going to a completely different screen. Sometimes we even forget that a script parameter is attached to a button, because it no longer shows up on that first screen.
Imagine that we have a whole bunch of buttons as the column headers of a list layout. Each button runs the same "Sort Records" script... but each button sorts the records in a different way, depending on its script parameter. It's so much easier & quicker & convenient to be able to check and/or change this script parameter on the first window instead of the second window.
The behavior from FileMaker Pro 13 and earlier is much preferred.