Controlling "Track: Set pan" with relative step size < 1% gets stuck at center

[helgoboss]

Experiments showed a somewhat strange behavior when it comes to setting track pan (via CSurf_OnPanChangeEx) to a value which is very close to center (0.01 ... so not many decimal places). After doing this, GetTrackUIVolPan still reports 0.0. Interestingly, this happens only with extensions, not in ReaScript (Lua). As always, I use Rust for the extension, but floating point numbers are the same as with C++ so this shouldn't matter.

Lua:

track = reaper.GetSelectedTrack(0, 0);
reaper.CSurf_OnPanChangeEx(track, 0.0, false, false);
ret, vol, panBefore = reaper.GetTrackUIVolPan(track);
reaper.CSurf_OnPanChangeEx(track, 0.01, false, false);
ret, vol, panAfter = reaper.GetTrackUIVolPan(track);

Rust:

// Given
reaper.csurf_on_pan_change_ex(track, Absolute(ReaperPanValue::new(0.0)), DenyGang);
let pan_before = reaper.get_track_ui_vol_pan(track)?.pan;
assert_eq!(pan_before.get(), 0.0);
// When
reaper.csurf_on_pan_change_ex(track, Absolute(ReaperPanValue::new(0.01)), DenyGang);
// Then
let pan_after = reaper.get_track_ui_vol_pan(track)?.pan;
assert_eq!(pan_after.get(), 0.0);

[helgoboss]

Justin found out that the difference is not between ReaScript vs. extension but between pressing control/command vs. not pressing it (when running a Lua ReaScript, I do this by pressing Ctrl+Enter). Will be fixed on REAPER side. Nevertheless I will try to implement something that detects "getting stuck" situations like this one.