For some of the songs I play with my band, I have music score images in Cantabile’s Show Notes, which I export from Sibelius as PNG, which I then need to scale using an image editor such as Gimp. Since score pages vary in height, this is not a trivially repeatable operation. The results are always average at best; sometimes depending on the scaling, the resulting score is fuzzy. So my first suggestion is for SVG support in Show Notes, so I can export SVG from Sibelius and have Cantabile render it optimally at whatever scale the Show Notes pane happens to be.
Often I stitch two pages together side by side using an image editor like Gimp, which is really laborious. So my second suggestion is for Show Notes to be able to support notes side by side. Perhaps just 1 or 2 notes horizontally would be enough, perhaps done by inserting a note and “splitting” it, or perhaps by an option on notes to say “The next note flows horizontally after this one”. I’m sure this would also be useful for other scenarios too, e.g. having a lyrics pane next to some other performance notes.
And my third suggestion, which is maybe a bit involved/ambitious, but may make the previous two suggestions redundant, is for Show Notes to embed a PDF, and for the note to have a state behaviour that selects which page of the PDF to show. This would mean you could export a full score from Sibelius or other notation software, reference the single file directly from Cantabile, and just dial up the appropriate page numbers for each song state. Even better, being able to show two adjacent pages. I don’t even know if this is possible, but it would certainly be wickedly useful for those of us who use score!!