Guitar Pro export does not show the embedded backing audio panel #3023

AI authorship

AI-assisted (disclosure block included).

Current Behavior

When I open a GP file exported by alphaTab with embedded backing audio in Guitar
Pro 8, the backing track is listed in the mixer but its audio panel is not open.

Expected Behavior

When opening a score that includes embedded backing audio, the audio panel should
be visible so the audio track can be inspected without first finding the panel
visibility control.

Steps To Reproduce

On the develop revision below, save this test as
packages/alphatab/test/exporter/AudioPanelRepro.test.ts and run
npm test --workspace=packages/alphatab -- test/exporter/AudioPanelRepro.test.ts.
It creates a short synthetic WAV tone inside audio-panel-repro.gp in the
packages/alphatab directory. Open that file in Guitar Pro 8:

import { Gp7Exporter } from '@coderline/alphatab/exporter/Gp7Exporter';
import { ScoreLoader } from '@coderline/alphatab/importer/ScoreLoader';
import { BackingTrack } from '@coderline/alphatab/model/BackingTrack';
import { writeFileSync } from 'node:fs';
import { it } from 'vitest';

it('creates a GP file with a backing track', () => {
    const samples = 44100;
    const wav = Buffer.alloc(44 + samples * 2);
    wav.write('RIFF', 0); wav.writeUInt32LE(wav.length - 8, 4);
    wav.write('WAVEfmt ', 8); wav.writeUInt32LE(16, 16);
    wav.writeUInt16LE(1, 20); wav.writeUInt16LE(1, 22);
    wav.writeUInt32LE(44100, 24); wav.writeUInt32LE(88200, 28);
    wav.writeUInt16LE(2, 32); wav.writeUInt16LE(16, 34);
    wav.write('data', 36); wav.writeUInt32LE(samples * 2, 40);
    for (let i = 0; i < samples; i++) {
        wav.writeInt16LE(Math.round(Math.sin(i * 2 * Math.PI * 440 / 44100) * 10000), 44 + i * 2);
    }
    const score = ScoreLoader.loadAlphaTex('3.3.4');
    score.backingTrack = new BackingTrack();
    score.backingTrack.rawAudioFile = wav;
    writeFileSync('audio-panel-repro.gp', new Gp7Exporter().export(score, null));
});

In my check, the Audio Track row was present, but the panel beneath the score
was closed. This check did not establish playback or synchronization behavior.

Version and Environment

[AlphaTab][VersionInfo] alphaTab 1.10.0
[AlphaTab][VersionInfo] commit: ec751a23f2e1f9601abb3ce2022300001c096565
[AlphaTab][VersionInfo] build date: 2026-11-08T22:36:57.508Z
[AlphaTab][VersionInfo] High DPI: 1
[AlphaTab][VersionInfo] Platform: NodeJs
[AlphaTab][VersionInfo] WebPack: false
[AlphaTab][VersionInfo] Vite: false
[AlphaTab][VersionInfo] Turbopack: false

Node.js 24.22.1 and Guitar Pro 8.1.4 Build 43 on Windows. The alphaTab
environment output was obtained with Environment.printEnvironmentInfo()
from the same unmodified develop revision.

Platform

Node.js