Maybe just adding an "Okay" button at the bottom for consistency (next to "Load/Save" button) - which would be basically the same as the "X" at the top, would be easy to do.
I had the same concerns when I started using MC.
As there is no way to actually cancel changes made in the DSP Studio anyway, I don't think there is an immediate need to build Cancel Button functionality. Everything done in the DSP Studio is saved, so just add an OK button as CountryBumkin suggests, and people would immediately understand how the dialogue functions. At least, I would have and I think others would also.
User opens the DSP Studio dialogue.
There is only an OK button and a Close using the "X" at the top.
User understands that the OK will save any changes and exit the dialogue.
User understands that the "X" will close the dialogue.
User makes changes and saves them using the OK button. Happy user.
Later, User makes changes in DSP Studio, tries to cancel them with the "X" button. Goes back in and finds changes still there. User not happy, but understands.
Compared with;
User opens the DSP Studio dialogue.
There is only a Close using the "X" at the top.
User doesn't understand how to save changes and exit the dialogue. User not happy.
User works out that the "X" will close the dialogue. Nervously tries it the first time in case all changes just made are lost.
User spends two hours testing that any change made in any part of DSP Studio are saved when dialogue is exited using the "X" at the top.
Later, User makes changes in DSP Studio, realizes they can't cancel them with the "X" button. User not happy, but understands. Spends time changing settings back.
Six months later, User comes back into DSP Studio to make some changes. Finishes 30 minutes work and realises there is no OK button. User thinks they remember that changes are saved when using the "X", but isn't sure. User presses the "X" to exit the dialogue, and immediately goes back in and checks all changes, spending another 10 minutes on the task. User not happy.
This sort of issue, combined with the limited documentation and the need to search a forum to get answers, is why lots of people think MC is only for geeks. I guess that in part answers Jim's question asked elsewhere. Unless a user lives with the software daily, and delves into it regularly, instead of just using it, MC requires some fiddling, testing, and time to use well. The vast majority of people want something close to an appliance, rather than a toolkit. But of course, they still want it to work with all the hardware and software they have, and they want it to work they way they want. But at least JRiver could take advantage of all the training Microsoft has indirectly put into all users.
I'll get off that soapbox now.