In Polyphone 1.8, when I click on a sample in the left panel, there's a dropdown to select sampling rate. However, if the sf2's sampling rate is not a standard choice in the box, the box appears empty. Additionally, I cannot type in custom sampling rates.
Maybe you should use a text+dropdown widget, instead of a dropdown?
I could add a line in the dropdown list when the sampling rate is not standard. For example the line "12345" if the sound has been recorded using 12345 samples / second.
For simplicity and respect of common sample rates, letting the user choosing its own rate would not be a good idea in my opinion. I may miss a case where choosing a specific sampling rate is useful.
