Excellent work on 2.7! I haven't found any major bugs so it's time to start nit-picking:
(Strangely enough, all of these are visualisation related.)
-When switching between visualisations, you can scroll from the "available visualisations" list to the very last vis. on the list by scrolling up. However, you can't do this if you have no extra visualisations installed.
-If you have extra visualisations installed, view one of them, then switch to either the Spectrum or the 3D Spectrum, then resize the info window downwards quickly. You'll be able to spot part of the last visualisation you watched.
-Also, switch to an installed visualisation, and then resize the window so it has the smallest possible height. Then switch to either the Spectrum or the 3D Spectrum. It will now have half the height it should! (Actually, it would nice if users could drag the Spectrums this small to begin with. For a real nostalgic experience, I was thinking of putting a hole in the Vintage skin where the Spectrum Analyzer would have gone, then resize the vis. to fit, and drag it underneath to cover the rest of the info window...
)
-Finally, some visualisations will now cause XMPlay to crash if they are resized (e.g. Hyperspec). Watch out for these.
So far that's all I've found! Again, great work!