diff --git a/README.md b/README.md
index 3ee6417..e99ca41 100644
--- a/README.md
+++ b/README.md
@@ -1,7 +1,16 @@
 The AntScope2 software is designed to support various models of RigExpert analyzers under various operating systems.
 
-Windows: QT5, QT Creator 2 and higher
+Windows: Qt6, Qt Creator 2 and higher
 
-Linux: to do
+Linux: Qt6, qmake. Build with:
+
+```
+qmake6 CONFIG+=release AntScope.pro
+make
+```
+
+Depends on `qt6-base`, `qt6-serialport`, `qt6-connectivity`, and `libusb` (used via the vendored HIDAPI backend for HID-connected analyzers). Packaged for Arch Linux/AUR as
+[`antscope2`](https://aur.archlinux.org/packages/antscope2) (pinned to a known-good commit, patched)
+and [`antscope2-git`](https://aur.archlinux.org/packages/antscope2-git) (tracks a patched branch's tip - see either package's `PKGBUILD` for the udev rule, desktop file, and data-path packaging details this repo's own build doesn't set up on its own).
 
 Mac OS: to do
diff --git a/analyzer/ble_analyzer.h b/analyzer/ble_analyzer.h
index 6fc0f9d..88f98fe 100644
--- a/analyzer/ble_analyzer.h
+++ b/analyzer/ble_analyzer.h
@@ -11,7 +11,6 @@
 #include <QDataStream>
 #include <QTimer>
 #include "baseanalyzer.h"
-#include "screeninfo.h"
 
 enum {
     BLE_VER_CMD = (quint8)0xE6,
@@ -194,7 +193,6 @@ private slots:
     void measuringChanged();
     void aliveChanged();
     void statsChanged();
-    void setScreenInfo(ScreenInfo& screen);
 
 private:
     QString m_error;
diff --git a/mainwindow.cpp b/mainwindow.cpp
index 680f693..0f9f767 100644
--- a/mainwindow.cpp
+++ b/mainwindow.cpp
@@ -536,7 +536,11 @@ MainWindow::MainWindow(QWidget *parent) :
 
     m_1secTimer = new QTimer(this);
     connect(m_1secTimer, SIGNAL(timeout()), this, SLOT(on_1secTimerTick()));
-    m_1secTimer->start(100);
+    m_1secTimer->start(1000);
+
+    m_focusDebounceTimer = new QTimer(this);
+    m_focusDebounceTimer->setSingleShot(true);
+    connect(m_focusDebounceTimer, &QTimer::timeout, this, &MainWindow::onFocusDebounceTimeout);
 
     loadLanguage(languages_small[m_languageNumber]);
     ui->tableWidget_presets->horizontalHeader()->show();
@@ -761,12 +765,15 @@ void MainWindow::closeEvent(QCloseEvent *event)
 
 bool MainWindow::event(QEvent * e)
 {
-    if(e->type() == QEvent::WindowActivate)
-    {
-        emit focus(true);
-    }else if (e->type() == QEvent::WindowDeactivate)
+    if(e->type() == QEvent::WindowActivate || e->type() == QEvent::WindowDeactivate)
     {
-        emit focus(false);
+        // Some window managers/compositors send rapid, sometimes
+        // continuous, Activate/Deactivate churn (e.g. triggered by an
+        // always-on-top Qt::Tool child being mapped/unmapped, which is
+        // itself a reaction to a previous Activate here - a feedback
+        // loop). Do not react to any single event; only act once the
+        // window's activation state has held steady for a while.
+        m_focusDebounceTimer->start(300);
     }else if (e->type() == QEvent::WindowStateChange)
     {
         updateGraph();
@@ -774,6 +781,15 @@ bool MainWindow::event(QEvent * e)
     return QMainWindow::event(e) ;
 }
 
+void MainWindow::onFocusDebounceTimeout()
+{
+    bool active = isActiveWindow();
+    if (active != m_lastEmittedFocus) {
+        m_lastEmittedFocus = active;
+        emit focus(active);
+    }
+}
+
 void MainWindow::setWidgetsSettings()
 {
     QPen pen;
@@ -6806,6 +6822,15 @@ void MainWindow::on_selectDeviceDialog()
         return;
     }
 
+    // dlg.exec() below runs a nested event loop, during which any other
+    // queued call to this same slot (e.g. a pending QTimer::singleShot
+    // from on_refreshConnection()) would still fire and stack a second
+    // SelectDeviceDialog on top of the first. Guard against that.
+    if (m_selectDeviceDialogOpen) {
+        return;
+    }
+    m_selectDeviceDialogOpen = true;
+
     SelectDeviceDialog dlg(false, this);
     if (dlg.exec() == QDialog::Accepted) {
         SelectionParameters sel_par = SelectionParameters::selected;
@@ -6815,6 +6840,7 @@ void MainWindow::on_selectDeviceDialog()
             emit m_analyzer->analyzerFound(selected->index());
         }
     }
+    m_selectDeviceDialogOpen = false;
     closeSettingsDialog();
     ui->settingsBtn->setEnabled(true);
 }
diff --git a/mainwindow.h b/mainwindow.h
index 5728d36..0354177 100644
--- a/mainwindow.h
+++ b/mainwindow.h
@@ -160,6 +160,8 @@ class MainWindow : public QMainWindow
 
 //    QTimer *m_redrawTimer;
     QTimer *m_1secTimer;
+    QTimer *m_focusDebounceTimer;
+    bool m_lastEmittedFocus = true;
 
     double m_cableVelFactor;
     double m_cableResistance;
@@ -199,6 +201,7 @@ class MainWindow : public QMainWindow
     bool m_addingMarker;
     bool m_isMouseClick;
     bool m_bInterrupted;
+    bool m_selectDeviceDialogOpen = false;
     QMap<QString, QStringList*> m_BandsMap;
     bool m_darkColorTheme = true;
     QPalette m_lightPalette;
@@ -338,6 +341,7 @@ private slots:
     void on_firmwareAutoUpdateStateChanged( bool state);
     void on_antScopeAutoUpdateStateChanged( bool state);
     void on_1secTimerTick();
+    void onFocusDebounceTimeout();
     void on_calibrationChanged();
     void on_SaveFile(int row, QString path);
     void on_mouseDoubleClick(QMouseEvent* e);
diff --git a/markers.cpp b/markers.cpp
index 663011f..55f9960 100644
--- a/markers.cpp
+++ b/markers.cpp
@@ -24,7 +24,7 @@ Markers::Markers(QObject *parent) : QObject(parent),
 
     if(m_markersHint == NULL)
     {
-        m_markersHint = new MarkersPopUp();
+        m_markersHint = new MarkersPopUp(MainWindow::m_mainWindow, true);
         m_markersHint->setHiding(false);
         if(m_markersHintEnabled && !m_markersList.isEmpty())
             m_markersHint->focusShow();
diff --git a/markers.h b/markers.h
index 663d78f..06942bb 100644
--- a/markers.h
+++ b/markers.h
@@ -103,7 +103,7 @@ class Markers : public QObject
 
     Measurements *m_measurements;
 
-    bool m_focus;
+    bool m_focus = true;
 
     double interpolate(double fq1, double fq2, double fq3, double param1, double param2);
 
diff --git a/markerspopup.cpp b/markerspopup.cpp
index 9274a04..d4d9138 100644
--- a/markerspopup.cpp
+++ b/markerspopup.cpp
@@ -5,7 +5,7 @@
 
 QMap<int, QString> MarkersHeaderColumn::m_mapHeader;
 
-MarkersPopUp::MarkersPopUp(QWidget *parent) : QWidget(parent),
+MarkersPopUp::MarkersPopUp(QWidget *parent, bool embedded) : QWidget(parent),
       m_durability(2000),
       m_hiding(true),
       m_x(0),
@@ -16,15 +16,23 @@ MarkersPopUp::MarkersPopUp(QWidget *parent) : QWidget(parent),
       m_mainY(0),
       m_mainBiasX(0),
       m_mainBiasY(0),
+      m_embedded(embedded),
       m_bgColor(0,0,0,180),
       m_penColor(255,255,255,180),
       m_textColor("white")
 {
-      setWindowFlags(Qt::FramelessWindowHint |        // Отключаем оформление окна
-                     Qt::Tool |                       // Отменяем показ в качестве отдельного окна
-                     Qt::WindowStaysOnTopHint);       // Устанавливаем поверх всех окон
+      if (m_embedded) {
+          // A plain child widget of its parent, not a separate top-level
+          // window - see PopUp::init() in popup.cpp for the full
+          // rationale (same fix, same class of bug).
+      } else {
+          setWindowFlags(Qt::FramelessWindowHint |        // Отключаем оформление окна
+                         Qt::Tool |                       // Отменяем показ в качестве отдельного окна
+                         Qt::WindowStaysOnTopHint |       // Устанавливаем поверх всех окон
+                         Qt::WindowDoesNotAcceptFocus);   // Никогда не становится активным окном
+          setAttribute(Qt::WA_ShowWithoutActivating);     // При показе, виджет не получается фокуса автоматически
+      }
       setAttribute(Qt::WA_TranslucentBackground);     // Указываем, что фон будет прозрачным
-      setAttribute(Qt::WA_ShowWithoutActivating);     // При показе, виджет не получается фокуса автоматически
 
       animation.setTargetObject(this);                // Устанавливаем целевой объект анимации
       animation.setPropertyName("popupOpacity");      // Устанавливаем анимируемое свойство
@@ -69,7 +77,20 @@ void MarkersPopUp::setName(QString name)
 
     m_settings->endGroup();
 
-    setGeometry(m_x,m_y,width(),height());
+    applyGeometry();
+}
+
+void MarkersPopUp::applyGeometry()
+{
+    // m_x/m_y are tracked as global screen coordinates throughout this
+    // class (mirrors PopUp::applyGeometry() in popup.cpp - see there for
+    // the full rationale).
+    if (m_embedded && parentWidget()) {
+        QPoint local = parentWidget()->mapFromGlobal(QPoint(m_x, m_y));
+        setGeometry(local.x(), local.y(), width(), height());
+    } else {
+        setGeometry(m_x, m_y, width(), height());
+    }
 }
 
 MarkersPopUp::~MarkersPopUp()
@@ -177,18 +198,31 @@ void MarkersPopUp::show()
 
 void MarkersPopUp::focusShow()
 {
-    //qDebug() << "MarkersPopUp::focusShow()" << m_menuVisible;
-    QWidget::show();
+    applyGeometry();
+    if (!isVisible()) {
+        QWidget::show();
+    }
+    if (m_embedded) {
+        raise();
+    }
 }
 
 void MarkersPopUp::focusHide()
 {
-    //qDebug() << "MarkersPopUp::focusHide()" << m_menuVisible;
     if (m_menuVisible) {
         setVisible(true);
         return;
     }
-    QWidget::hide();
+    if (m_embedded) {
+        // A plain child widget: hiding it does not touch any top-level
+        // window, so there is no compositor feedback-loop risk here.
+        QWidget::hide();
+        return;
+    }
+    // Park off-screen instead of QWidget::hide(): see PopUp::focusHide()
+    // for why unmapping this Qt::Tool surface causes a feedback loop on
+    // some Wayland compositors.
+    move(-32000, -32000);
 }
 
 void MarkersPopUp::hideAnimation()
@@ -230,10 +264,7 @@ void MarkersPopUp::mouseMoveEvent(QMouseEvent * )
 {
     m_x = QCursor::pos().x() - m_biasX;
     m_y = QCursor::pos().y() - m_biasY;
-    setGeometry(m_x,
-                m_y,
-                width(),
-                height());
+    applyGeometry();
     m_mainBiasX = m_x - m_mainX;
     m_mainBiasY = m_y - m_mainY;
 }
@@ -245,20 +276,14 @@ void MarkersPopUp::MainWindowPos(int x, int y)
 
     m_x = x + m_mainBiasX;
     m_y = y + m_mainBiasY;
-    setGeometry(m_x,
-                m_y,
-                width(),
-                height());
+    applyGeometry();
 }
 
 void MarkersPopUp::setPosition(int x, int y)
 {
     m_x = x;
     m_y = y;
-    setGeometry(m_x,
-                m_y,
-                width(),
-                height());
+    applyGeometry();
 }
 
 void MarkersPopUp::setTextColor(QString color)
diff --git a/markerspopup.h b/markerspopup.h
index 1e01476..fffcece 100644
--- a/markerspopup.h
+++ b/markerspopup.h
@@ -43,7 +43,7 @@ class MarkersPopUp : public QWidget
     float getPopupOpacity() const;
 
 public:
-    explicit MarkersPopUp(QWidget *parent = 0);
+    explicit MarkersPopUp(QWidget *parent = 0, bool embedded = false);
     ~MarkersPopUp();
     void setName(QString name);
     int getDurability (void) const {return m_durability;}
@@ -125,6 +125,12 @@ private slots:
     int m_parentX;
     int m_parentY;
 
+    // When true, this MarkersPopUp is a plain child widget of its parent
+    // rather than a separate Qt::Tool top-level window - see
+    // markerspopup.cpp for why.
+    bool m_embedded;
+    void applyGeometry();
+
     QColor m_bgColor;
     QColor m_penColor;
     QString m_textColor;
diff --git a/measurements.cpp b/measurements.cpp
index 1cccef7..fe2d204 100644
--- a/measurements.cpp
+++ b/measurements.cpp
@@ -89,7 +89,7 @@ Measurements::Measurements(QObject *parent) : QObject(parent),
 
     if(m_graphHint == NULL)
     {
-        m_graphHint = new PopUp();
+        m_graphHint = new PopUp(MainWindow::m_mainWindow, true);
         m_graphHint->setHiding(false);
         m_settings->beginGroup("Settings");
         bool darkTheme = m_settings->value("darkColorTheme", true).toBool();
@@ -116,7 +116,7 @@ Measurements::Measurements(QObject *parent) : QObject(parent),
 
     if(m_graphBriefHint == NULL)
     {
-        m_graphBriefHint = new PopUp();
+        m_graphBriefHint = new PopUp(MainWindow::m_mainWindow, true);
         m_graphBriefHint->setHiding(false);
         //m_graphBriefHint->setPopupText("0\n0");
         m_graphBriefHint->setName(tr("BriefHint"));
diff --git a/measurements.h b/measurements.h
index 41be83b..318ba37 100644
--- a/measurements.h
+++ b/measurements.h
@@ -216,7 +216,7 @@ class Measurements : public QObject
     qint32 m_farEndMeasurement;
     QCPItemEllipse * m_smithTracer;
 
-    bool m_focus;
+    bool m_focus = true;
 
     bool m_oneFqMode = false;
     qint64 m_oneFqStartTime;
diff --git a/onefqwidget.cpp b/onefqwidget.cpp
index b83bf1d..e93011d 100644
--- a/onefqwidget.cpp
+++ b/onefqwidget.cpp
@@ -28,7 +28,7 @@ OneFqWidget::OneFqWidget(int _points, QWidget *parent) :
     setAttribute(Qt::WA_ShowWithoutActivating);
 
     m_label.setAlignment(Qt::AlignLeft | Qt::AlignVCenter);
-    m_label.setStyleSheet("QLabel { color : " + m_textColor.name() +
+    m_label.setStyleSheet("QLabel { color : " + m_textColor.name() + ";"
                         "margin-top: 6px;"
                         "margin-bottom: 6px;"
                         "margin-left: 10px;"
diff --git a/popup.cpp b/popup.cpp
index 0eff1ac..a8c772e 100644
--- a/popup.cpp
+++ b/popup.cpp
@@ -5,7 +5,7 @@
 #include <QDebug>
 #include <mainwindow.h>
 
-PopUp::PopUp(QWidget *parent) : QWidget(parent),
+PopUp::PopUp(QWidget *parent, bool embedded) : QWidget(parent),
     m_bgColor(0,0,0,180),
     m_penColor(255,155,255,180),
     m_textColor("white"),
@@ -19,12 +19,13 @@ PopUp::PopUp(QWidget *parent) : QWidget(parent),
     m_mainX(177),
     m_mainY(131),
     m_mainBiasX(0),
-    m_mainBiasY(0)
+    m_mainBiasY(0),
+    m_embedded(embedded)
 {
     init();
 }
 
-PopUp::PopUp(QString buttonName, QWidget *parent) : QWidget(parent),
+PopUp::PopUp(QString buttonName, QWidget *parent, bool embedded) : QWidget(parent),
     m_bgColor(0,0,0,180),
     m_penColor(255,155,255,180),
     m_textColor("white"),
@@ -40,25 +41,35 @@ PopUp::PopUp(QString buttonName, QWidget *parent) : QWidget(parent),
     m_mainBiasX(0),
     m_mainBiasY(0),
     m_buttonName(buttonName),
-    m_showButton(true)
+    m_showButton(true),
+    m_embedded(embedded)
 {
     init();
 }
 
 void PopUp::init()
 {
-    setWindowFlags(Qt::FramelessWindowHint |
-                   Qt::Tool |
-                   Qt::WindowStaysOnTopHint);
+    if (m_embedded) {
+        // A plain child widget of its parent, not a separate top-level
+        // window: there is no window for a window manager/compositor to
+        // ever see, so this cannot perturb the parent's activation state
+        // (see focusShow()/focusHide()) and it cannot show up in any
+        // window/task list either.
+    } else {
+        setWindowFlags(Qt::FramelessWindowHint |
+                       Qt::Tool |
+                       Qt::WindowStaysOnTopHint |
+                       Qt::WindowDoesNotAcceptFocus);
+        setAttribute(Qt::WA_ShowWithoutActivating);
+    }
     setAttribute(Qt::WA_TranslucentBackground);
-    setAttribute(Qt::WA_ShowWithoutActivating);
 
     animation.setTargetObject(this);
     animation.setPropertyName("popupOpacity");
     connect(&animation, &QAbstractAnimation::finished, this, &PopUp::hide);
 
     label.setAlignment(Qt::AlignLeft | Qt::AlignVCenter);
-    label.setStyleSheet("QLabel { color : " + m_textColor +
+    label.setStyleSheet("QLabel { color : " + m_textColor + ";"
                         "margin-top: 6px;"
                         "margin-bottom: 6px;"
                         "margin-left: 10px;"
@@ -119,7 +130,23 @@ void PopUp::setName(QString name)
 
     m_settings->endGroup();
 
-    setGeometry(m_x,m_y,width(),height());
+    applyGeometry();
+}
+
+void PopUp::applyGeometry()
+{
+    // m_x/m_y are tracked as global screen coordinates throughout this
+    // class (MainWindowPos(), mouseMoveEvent() and every caller of
+    // setPosition() all compute them that way, matching the original
+    // Qt::Tool top-level design). When embedded as a child widget,
+    // translate to parent-relative coordinates right here instead of
+    // touching that positioning math anywhere else.
+    if (m_embedded && parentWidget()) {
+        QPoint local = parentWidget()->mapFromGlobal(QPoint(m_x, m_y));
+        setGeometry(local.x(), local.y(), width(), height());
+    } else {
+        setGeometry(m_x, m_y, width(), height());
+    }
 }
 
 PopUp::~PopUp()
@@ -185,12 +212,33 @@ void PopUp::show()
 
 void PopUp::focusShow()
 {
-    QWidget::show();
+    applyGeometry();
+    if (!isVisible()) {
+        QWidget::show();
+    }
+    if (m_embedded) {
+        raise();
+    }
 }
 
 void PopUp::focusHide()
 {
-    QWidget::hide();
+    if (m_embedded) {
+        // A plain child widget: hiding it does not touch any top-level
+        // window, so there is no compositor feedback-loop risk here -
+        // see the Qt::Tool branch below for what that risk was.
+        QWidget::hide();
+        return;
+    }
+    // Park off-screen instead of QWidget::hide(): unmapping this
+    // Qt::Tool top-level surface causes some Wayland compositors
+    // (observed on COSMIC/cosmic-comp) to send a spurious
+    // WindowActivate/WindowDeactivate event to the parent window. Since
+    // that event drives this same show/hide logic (via MainWindow::event
+    // -> focus() -> showHideHints()), unmapping creates a self-sustaining
+    // feedback loop ("flickering popups"). Moving off-screen is visually
+    // equivalent while keeping the surface continuously mapped.
+    move(-32000, -32000);
 }
 
 void PopUp::hideAnimation()
diff --git a/popup.h b/popup.h
index b8a48e3..dcda853 100644
--- a/popup.h
+++ b/popup.h
@@ -21,8 +21,8 @@ class PopUp : public QWidget
     float getPopupOpacity() const;
 
 public:
-    explicit PopUp(QWidget *parent = 0);
-    explicit PopUp(QString button, QWidget *parent = 0);
+    explicit PopUp(QWidget *parent = 0, bool embedded = false);
+    explicit PopUp(QString button, QWidget *parent = 0, bool embedded = false);
     ~PopUp();
     void init();
     void setName(QString name);
@@ -104,6 +104,10 @@ protected slots:
     int m_parentX;
     int m_parentY;
 
+    // When true, this PopUp is a plain child widget of its parent rather
+    // than a separate Qt::Tool top-level window - see popup.cpp for why.
+    bool m_embedded;
+    void applyGeometry();
 
     QString m_name;