There are many things to consider which would make such a feature all but trivial to implement:

• Sample playback speed and envelope playback speed are not synchronized. If you transpose a sample one octave up, it will play twice as fast, but the envelope keeps playing at its original speed. Thus the sample could only be drawn after previewing a note, because it has to be known at which speed to play a sample.
• Instruments can be multisampled. Another reason why the sample can only be shown after previewing a note.
• Things get really messy once you enable pitch envelopes, because the pitch envelope obviously affects the synchronization between sample and envelopes just the same way as playing the sample at a different pitch.
• Similarly, if the sample has auto-vibrato set, the synchronization would change on every tick. But the changes are small and cyclic, so it could probably be ignored.

Only allowing this to work for middle-C and one sample would rule out many useful use cases and just make the feature much less useful (and harder to understand), so I would not consider implementing it without considering the limiting factors mentioned above. In particular, ignoring the pitch envelope could be very misleading.

All good points, to be sure. And i knew this would create a display nightmare.

Pitch and filter envelopes would definitely be more than what i was wishing for, and that nightmare is not yet worth pursuing.

I guess what i'm looking for is some kind of display to show how the volume envelope affects whatever audio i'm applying it to. For my purposes, i'm generally affixing envelopes to samples that i will not be playing at different notes, which is why it was acceptable to preview the sync (between sample and envelope) at a given note.

We should brainstorm another way, maybe?