Method buildDisplayPanel

src/gui/SpectrumOverlayMenu.cpp:1216–1919

// ── Display sub-panel ─────────────────────────────────────────────────────────

void SpectrumOverlayMenu::buildDisplayPanel()
{
    m_displayPanel = new QWidget(parentWidget());
    AetherSDR::ThemeManager::instance().applyStyleSheet(m_displayPanel, "QWidget { background: rgba(15, 15, 26, 220); "
                                   "border: 1px solid {{color.background.2}}; border-radius: 3px; }");
    m_displayPanel->hide();

    auto* grid = new QGridLayout(m_displayPanel);
    grid->setContentsMargins(8, 6, 8, 6);
    grid->setSpacing(4);
    grid->setColumnStretch(1, 1);

    auto labelStyle = QStringLiteral("QLabel { color: #8090a0; font-size: 10px; border: none; }");
    auto valStyle   = QStringLiteral("QLabel { color: #c8d8e8; font-size: 10px; border: none;"
                                      " min-width: 24px; }");
    auto btnStyle = QStringLiteral(
        "QPushButton { background: #1a2a3a; color: #c8d8e8; border: 1px solid #205070;"
        " border-radius: 3px; font-size: 10px; font-weight: bold; padding: 2px 6px; }"
        "QPushButton:hover { background: #204060; }"
        "QPushButton:checked { background: #006040; color: #00ff88; border-color: #00a060; }");

    int row = 0;
    // Grid columns: 0=label, 1=button (optional), 2=slider, 3=value

    // Helper: label col 0, slider col 1-2, value col 3
    auto makeRow = [&](const QString& text, int lo, int hi, int def,
                       QSlider*& slider, QLabel*& valLbl) {
        auto* lbl = new QLabel(text);
        lbl->setStyleSheet(labelStyle);
        grid->addWidget(lbl, row, 0);

        slider = new GuardedSlider(Qt::Horizontal);
        slider->setRange(lo, hi);
        slider->setValue(def);
        applyPrimarySliderStyle(slider);
        grid->addWidget(slider, row, 1, 1, 2);

        valLbl = new QLabel(QString::number(def));
        valLbl->setStyleSheet(valStyle);
        valLbl->setFixedWidth(28);
        valLbl->setAlignment(Qt::AlignRight | Qt::AlignVCenter);
        grid->addWidget(valLbl, row, 3);
        ++row;
    };

    // Helper: label col 0, button col 1, slider col 2, value col 3
    auto makeRowWithBtn = [&](const QString& text, int lo, int hi, int def,
                              QSlider*& slider, QLabel*& valLbl,
                              QPushButton*& btn, const QString& btnText) {
        auto* lbl = new QLabel(text);
        lbl->setStyleSheet(labelStyle);
        grid->addWidget(lbl, row, 0);

        btn = new QPushButton(btnText);
        btn->setCheckable(true);
        btn->setFixedSize(36, 18);
        btn->setStyleSheet(btnStyle);
        grid->addWidget(btn, row, 1);