What if the line that shows where in the sample it is currently at, would be less emphasized depending on the note volume / the instrument envelope ?
Maybe its a stupid idea. 
Also another GUI-idea: When the song auto-saves (and you can’t edit), darken the screen just like when in “Render to disk”-mode, to visualize that you can’t edit anything at the moment.
I recently did and finished a remix during a couple of days. I have autosave set to every 15 minutes and it still frustrated me everytime when I was hitting notes and nothing happened, just before realising that it was saving a backup. I kept thinking of this, if the Renoise-screen had darkened (this is connected to “Enable GUI effects”) while saving in the same way as when the rendering screen is active, it would give a greater feedback that a backup was going on.
Just like to know how everyone feels about this? Or maybe you’re not as irritated by distractions of the workflow (which is otherwise kept very nice in Renoise, mind I say) as I am. 