How much "missing" space are we talking about? If a few pixels it might that some OSX component is a tad larger on the new machine (was the same OSX version?)
I got an app called display menu and that enables the full resolution (and any size in between)... Which is not really readable for serious development work, but it's great for debugging of seeing the larger picture :-)
It is about 25%± smaller on most screens. However, on the startup screen it is 50%±, which I should be able to adjust quite simply.
In FileMaker Pro 14, the Get(ScreenHeight) and Get(ScreenWidth) functions return the size in 'points', not pixels, which is why it is reporting the same screen size as the older MacBook... You can use Get(ScreenScaleFactor) to get relative pixel density of the display, e.g. returns '1' for device without retina, '2' for Retina Mac or iPhone 6, and '3' for iPhone 6 Plus...
Does seem odd that you are having to scroll when you didn't before... Is it something as simple as having the Dock at the bottom of your screen displayed larger than before?
The display is not larger. Retina display will still be at the same resolution but the contents will be rendered at a higher resolution,
and scaled back down approximately x2.
The technicalities are complicated. Because the display has more pixels and FileMaker uses points, a point size will be recalculated to roughly 4 pixels large instead of 1. I'm not even claiming I understand it.
I have my retina display scaling set to one higher than the default before I need glasses.
Also my layouts are sized to 1440 by 840, not by the full 900.
Do you have to scroll vertical, horizontal or both?
A friend found the answer. I had to go into Displays Control Panel and change settings from Default for display to Scaled and set the option to the right of the Default.