Ability to lock vertical zoom for individual tracks
I sometimes have one or more tracks that I want to keep fairly tall all the time so I can see their audio in more detail, while other tracks can usually stay as small (vertically) as possible. But when I do need to zoom those small ones and then zoom them all the way back out, my tall ones also get zoomed out. If I could lock them, I'd be much happier.
A variation on this idea would be zooming proportionally when some tracks have been individually zoomed, so the small ones get bigger and the big ones get even bigger. When you zoom back out, the small ones go to smallest possible and the tall ones go back to where the heights that were previously set.

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Jordan Nash commented
I concur with all of your suggestions on this. Vertical zooming could stand some improvement in Audition.
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Olaf Nelson commented
And one more: option to have mouse wheel/trackpad only vertically zoom the track that the mouse pointer/cursor/whatever is hovering over.
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Olaf Nelson commented
Another feature that would be cool: ability to use mouse wheel or laptop trackpad to vertically zoom just the tracks in a group, leaving all other tracks's sizes unchanged.