Always use the fn key together with Return to close the calc window (this is on a laptop w/o an Enter key)
I believe the difference is caused by what area is active within the calculation window.
I attached 2 example files. In the first, the calculation box is active. Notice the blue border around the box.
If you press Return now, you are entered a Return character into the box.
In example 2, the Calculation Result is Number is selected or active.
If you press Return now, it is the same as clicking on the OK button.
I moved from one active area to the next using the Tab key on the keyboard.
I don't remember exactly when this behavior came about, but I think it has to do with the OS as well as FM capabilities.
It gives us the ability to move within a window, selecting different options and have them be active when we need them, using the Keyboard and not the Mouse. Nice feature, but it may take a bit of getting used to.
The default when you open the calculation Window is the calculation box.
Hi Kevin et al,
I recommend that you download and install KeyRemap4MacBook as a Preference pane. With it you can convert the RH Option Key to the Enter Key sparing any need to always remember fn-Return when you genuinely need to use Enter.
I've certainly not seen it cause any unintended side effects with OS X 10.6.8 on my latest MacBook Pro.
In addition to Michele's comments …
I don't know if this is relevant or not, but there is a difference in behaviour between the full calculation engine window and the simpler one you get initially when you specify, for example, a Set Variable Step:
Hitting Return or Enter in this a window always activates the OK button