I guess the proper place for x-sonicvisualiser.desktop & x-sonicvisualiser-layer.desktop would be /usr/share/mimelnk/application (still doesn't help with .sv being application/x-sonicvisualiser & .svl being application/x-sonicvisualiser-layer
I guess the proper place for x-sonicvisualis er.desktop & x-sonicvisualis er-layer. desktop would be /usr/share/ mimelnk/ application x-sonicvisualis er & .svl being application/ x-sonicvisualis er-layer
(still doesn't help with .sv being application/