General problem with Audio Units or VSTs inside foobar2000 is that you can either visualize accurately (feed live audio being heard) or control settings and feed audio being processed by this instance of the AU/VST (choppy/lagged performance of AU/VST that shows audio being played).
I just added (build 2024-07-04) a separate, probably more useful mode: add mode=control to the layout line - audio data being fed isn't synchronized with playback but changes in AU settings are applied to current DSP configuration.
This is nice. There's a small bug in that the embedded AU sometimes forgets its size and I have to resize it and the panel that contains it.
AU aside, there's an odd bug. This AU-free layout
splitter vertical style=thin
splitter horizontal style=thin
tabs position=top
splitter horizontal style=thin tab-name="Playlists"
playlist-picker
albumart type="front cover"
albumlist tab-name="Library"
splitter horizontal style=thin tab-name="Info"
selection-properties sections="General"
console mode=lite
splitter horizontal style=thin
refacets
splitter horizontal style=thin
playlist
playback-controls
has playback-controls on the right side of a vertical split. This causes the left pane to resize itself to take up half the window no matter how you move the splitter.
OTOTH this layout
splitter horizontal style=thin
splitter vertical style=thin
splitter horizontal style=thin
splitter horizontal style=thin
tabs position=top
splitter horizontal style=thin tab-name="Playlists"
playlist-picker
albumart type="front cover"
albumlist tab-name="Library"
splitter horizontal style=thin tab-name="Info"
selection-properties sections="General"
console mode=lite
splitter horizontal style=thin
refacets
playlist
playback-controls
which is almost identical but puts the playback-controls at the bottom and lets it take up the whole width of the window, is ok. It's as if having playback-controls this way properly constrains the left pane.
I think this bug was fixed one or two previews ago and regressed with the 2024-07-08 version