diff --git a/Software/PC_Application/LibreVNA-GUI/SpectrumAnalyzer/tracewidgetsa.cpp b/Software/PC_Application/LibreVNA-GUI/SpectrumAnalyzer/tracewidgetsa.cpp
index 545ee85..d9d46c9 100644
--- a/Software/PC_Application/LibreVNA-GUI/SpectrumAnalyzer/tracewidgetsa.cpp
+++ b/Software/PC_Application/LibreVNA-GUI/SpectrumAnalyzer/tracewidgetsa.cpp
@@ -8,7 +8,7 @@
 #include <QFileDialog>
 
 TraceWidgetSA::TraceWidgetSA(TraceModel &model, QWidget *parent)
-    : TraceWidget(model, parent)
+    : TraceWidget(model, nullptr, nullptr, parent)
 {
 
 }
@@ -20,32 +20,3 @@ void TraceWidgetSA::exportDialog()
         csv->show();
     }
 }
-
-void TraceWidgetSA::importDialog()
-{
-    auto filename = QFileDialog::getOpenFileName(nullptr, "Open measurement file", "", "CSV files (*.csv)", nullptr, Preferences::QFileDialogOptions());
-    if (!filename.isEmpty()) {
-        try {
-            std::vector<Trace*> traces;
-            QString prefix = QString();
-            auto csv = CSV::fromFile(filename);
-            traces = Trace::createFromCSV(csv);
-            // contruct prefix from filename
-            prefix = filename;
-            // remove any directory names (keep only the filename itself)
-            int lastSlash = qMax(prefix.lastIndexOf('/'), prefix.lastIndexOf('\\'));
-            if(lastSlash != -1) {
-                prefix.remove(0, lastSlash + 1);
-            }
-            // remove file type
-            prefix.truncate(prefix.indexOf('.'));
-            prefix.append("_");
-            auto i = new TraceImportDialog(model, traces, prefix);
-            if(AppWindow::showGUI()) {
-                i->show();
-            }
-        } catch(const std::exception &e) {
-            InformationBox::ShowError("Failed to import file", QString("Attempt to import file ended with error: \"") + e.what()+"\"");
-        }
-    }
-}
diff --git a/Software/PC_Application/LibreVNA-GUI/SpectrumAnalyzer/tracewidgetsa.h b/Software/PC_Application/LibreVNA-GUI/SpectrumAnalyzer/tracewidgetsa.h
index 5e24244..52c2201 100644
--- a/Software/PC_Application/LibreVNA-GUI/SpectrumAnalyzer/tracewidgetsa.h
+++ b/Software/PC_Application/LibreVNA-GUI/SpectrumAnalyzer/tracewidgetsa.h
@@ -9,7 +9,7 @@ public:
     TraceWidgetSA(TraceModel &model, QWidget *parent = nullptr);
 public slots:
     virtual void exportDialog() override;
-    virtual void importDialog() override;
+    virtual QStringList supportsImportFileFormats() override {return {"csv"};}
 
 protected:
     virtual QString defaultParameter() override {return "PORT1";}
diff --git a/Software/PC_Application/LibreVNA-GUI/Traces/traceaxis.cpp b/Software/PC_Application/LibreVNA-GUI/Traces/traceaxis.cpp
index aafdb50..55c457e 100644
--- a/Software/PC_Application/LibreVNA-GUI/Traces/traceaxis.cpp
+++ b/Software/PC_Application/LibreVNA-GUI/Traces/traceaxis.cpp
@@ -352,6 +352,7 @@ std::set<YAxis::Type> YAxis::getSupported(XAxis::Type type, TraceModel::DataSour
     } else if(source == TraceModel::DataSource::SA) {
         switch(type) {
         case XAxis::Type::Frequency:
+        case XAxis::Type::TimeZeroSpan:
             ret.insert(YAxis::Type::Magnitude);
             ret.insert(YAxis::Type::MagnitudedBuV);
             break;
diff --git a/Software/PC_Application/LibreVNA-GUI/Traces/traceplot.cpp b/Software/PC_Application/LibreVNA-GUI/Traces/traceplot.cpp
index e5f567c..94537a6 100644
--- a/Software/PC_Application/LibreVNA-GUI/Traces/traceplot.cpp
+++ b/Software/PC_Application/LibreVNA-GUI/Traces/traceplot.cpp
@@ -626,7 +626,6 @@ void TracePlot::dragMoveEvent(QDragMoveEvent *event)
         // transform to relative coordinates from 0 to 1
         auto x = (double) pos.x() / (width() - marginLeft - marginRight);
         auto y = (double) pos.y() / (height() - marginTop - marginBottom);
-        qDebug() << "x:" << x << "y:" << y;
         if(y < 0.5) {
             if(x < y) {
                 dropSection = DropSection::ToTheLeft;
diff --git a/Software/PC_Application/LibreVNA-GUI/Traces/tracewidget.cpp b/Software/PC_Application/LibreVNA-GUI/Traces/tracewidget.cpp
index b524ded..729a068 100644
--- a/Software/PC_Application/LibreVNA-GUI/Traces/tracewidget.cpp
+++ b/Software/PC_Application/LibreVNA-GUI/Traces/tracewidget.cpp
@@ -3,6 +3,8 @@
 #include "ui_tracewidget.h"
 #include "traceeditdialog.h"
 #include "traceimportdialog.h"
+#include "ui_s2pImportOptions.h"
+#include "CustomWidgets/informationbox.h"
 #include "tracetouchstoneexport.h"
 #include "trace.h"
 #include "unit.h"
@@ -16,14 +18,17 @@
 #include <QDebug>
 #include <QMenu>
 #include <QTableView>
+#include <QDebug>
 
-
-TraceWidget::TraceWidget(TraceModel &model, QWidget *parent) :
+TraceWidget::TraceWidget(TraceModel &model, Calibration *cal, Deembedding *deembed, QWidget *parent) :
     QWidget(parent),
     SCPINode("TRACe"),
     dragTrace(nullptr),
     ui(new Ui::TraceWidget),
-    model(model)
+    model(model),
+    dropFilename(""),
+    cal(cal),
+    deembed(deembed)
 {
     ui->setupUi(this);
     ui->view->setModel(&model);
@@ -37,6 +42,7 @@ TraceWidget::TraceWidget(TraceModel &model, QWidget *parent) :
         ui->remove->setEnabled(current.isValid());
     });
     installEventFilter(this);
+    setAcceptDrops(true);
     createCount = 0;
     SetupSCPI();
 }
@@ -119,6 +125,41 @@ bool TraceWidget::eventFilter(QObject *, QEvent *event)
     return false;
 }
 
+void TraceWidget::dragEnterEvent(QDragEnterEvent *event)
+{
+    if(event->mimeData()->hasFormat("text/plain")) {
+        // might be a file drop
+        auto data = QString(event->mimeData()->data("text/plain"));
+        if (data.startsWith("file://")) {
+            // extract file path/name and type
+            data = data.trimmed();
+            data.remove(0, 7);
+            if(data.contains(".")) {
+                auto type = data.split(".").last();
+                if (supportsImportFileFormats().contains(type)) {
+                    dropFilename = data;
+                    qDebug() << "prepared to drop file " << dropFilename;
+                    event->accept();
+                    return;
+                }
+            }
+        }
+    }
+    event->ignore();
+    dropFilename = "";
+ }
+
+void TraceWidget::dropEvent(QDropEvent *event)
+{
+    Q_UNUSED(event);
+    if(dropFilename.size() > 0) {
+        if(importFile(dropFilename)) {
+            event->accept();
+        }
+    }
+    dropFilename = "";
+}
+
 void TraceWidget::on_edit_clicked()
 {
     if(ui->view->currentIndex().isValid()) {
@@ -159,6 +200,111 @@ void TraceWidget::on_view_clicked(const QModelIndex &index)
     }
 }
 
+void TraceWidget::importDialog()
+{
+    QString supported = "Supported files (";
+    for(auto f : supportsImportFileFormats()) {
+        supported += "*."+f+" ";
+    }
+    supported.chop(1);
+    supported += ")";
+    auto filename = QFileDialog::getOpenFileName(nullptr, "Open measurement file", "", supported, nullptr, Preferences::QFileDialogOptions());
+    if (!filename.isEmpty()) {
+        importFile(filename);
+    }
+}
+
+bool TraceWidget::importFile(QString filename)
+{
+    if(!filename.contains(".")) {
+        // no ending, not supported
+        return false;
+    }
+    auto format = filename.split(".").last();
+    if(!supportsImportFileFormats().contains(format)) {
+        // unsupported format
+        return false;
+    }
+    // try to import the file
+    try {
+        std::vector<Trace*> traces;
+        int touchstonePorts = 0;
+        QString prefix = QString();
+        if(filename.endsWith(".csv")) {
+            auto csv = CSV::fromFile(filename);
+            traces = Trace::createFromCSV(csv);
+        } else {
+            // must be a touchstone file
+            auto t = Touchstone::fromFile(filename.toStdString());
+            traces = Trace::createFromTouchstone(t);
+            touchstonePorts = t.ports();
+        }
+        // contruct prefix from filename
+        prefix = filename;
+        // remove any directory names (keep only the filename itself)
+        int lastSlash = qMax(prefix.lastIndexOf('/'), prefix.lastIndexOf('\\'));
+        if(lastSlash != -1) {
+            prefix.remove(0, lastSlash + 1);
+        }
+        // remove file type
+        prefix.truncate(prefix.indexOf('.'));
+        prefix.append("_");
+        auto i = new TraceImportDialog(model, traces, prefix);
+        if(AppWindow::showGUI()) {
+            i->show();
+        }
+        // potential candidate to process via calibration/de-embedding
+        connect(i, &TraceImportDialog::importFinsished, [=](const std::vector<Trace*> &traces) {
+            if(traces.size() == touchstonePorts*touchstonePorts) {
+                // all traces imported, can calculate calibration/de-embedding
+                bool calAvailable = cal && cal->getNumPoints() > 0;
+                bool deembedAvailable = deembed && deembed->getOptions().size() > 0;
+                if(calAvailable || deembedAvailable) {
+                    // check if user wants to apply either one to the imported traces
+                    auto dialog = new QDialog();
+                    auto ui = new Ui::s2pImportOptions;
+                    ui->setupUi(dialog);
+                    connect(dialog, &QDialog::finished, [=](){
+                        delete ui;
+                    });
+                    ui->applyCal->setEnabled(calAvailable);
+                    ui->deembed->setEnabled(deembedAvailable);
+                    bool applyCal = false;
+                    bool applyDeembed = false;
+                    connect(ui->applyCal, &QCheckBox::toggled, [&](bool checked) {
+                        applyCal = checked;
+                    });
+                    connect(ui->deembed, &QCheckBox::toggled, [&](bool checked) {
+                        applyDeembed = checked;
+                    });
+                    if(AppWindow::showGUI()) {
+                        dialog->exec();
+                    }
+                    // assemble trace set
+                    std::map<QString, Trace*> set;
+                    for(int i=1;i<=touchstonePorts;i++) {
+                        for(int j=1;j<=touchstonePorts;j++) {
+                            QString name = "S"+QString::number(i)+QString::number(j);
+                            int index = (i-1)*touchstonePorts+(j-1);
+                            set[name] = traces[index];
+                        }
+                    }
+                    if(applyCal) {
+                        cal->correctTraces(set);
+                    }
+                    if(applyDeembed) {
+                        deembed->Deembed(set);
+                    }
+                }
+            }
+        });
+        return true;
+    } catch(const std::exception& e) {
+        InformationBox::ShowError("Failed to import file", QString("Attempt to import file ended with error: \"") + e.what()+"\"");
+        return false;
+    }
+}
+
 void TraceWidget::SetupSCPI()
 {
     auto findTraceFromName = [=](QString name) -> Trace* {
diff --git a/Software/PC_Application/LibreVNA-GUI/Traces/tracewidget.h b/Software/PC_Application/LibreVNA-GUI/Traces/tracewidget.h
index 223b5cc..d4ffcfa 100644
--- a/Software/PC_Application/LibreVNA-GUI/Traces/tracewidget.h
+++ b/Software/PC_Application/LibreVNA-GUI/Traces/tracewidget.h
@@ -3,6 +3,8 @@
 
 #include "tracemodel.h"
 #include "scpi.h"
+#include "Calibration/calibration.h"
+#include "VNA/Deembedding/deembedding.h"
 
 #include <QWidget>
 
@@ -15,28 +17,40 @@ class TraceWidget : public QWidget, public SCPINode
     Q_OBJECT
 
 public:
-    explicit TraceWidget(TraceModel &model, QWidget *parent = nullptr);
+    explicit TraceWidget(TraceModel &model, Calibration *cal, Deembedding *deembed, QWidget *parent = nullptr);
     virtual ~TraceWidget();
 
+public:
+    virtual void exportDialog() = 0;
+    virtual void importDialog();
+
 protected slots:
     void on_add_clicked();
     void on_remove_clicked();
     void on_edit_clicked();
     void on_view_doubleClicked(const QModelIndex &index);
     void on_view_clicked(const QModelIndex &index);
-    virtual void exportDialog() = 0;
-    virtual void importDialog() = 0;
+    virtual QStringList supportsImportFileFormats() = 0;
+    bool importFile(QString filename);
 
 protected:
     void SetupSCPI();
     void contextMenuEvent(QContextMenuEvent *event) override;
     bool eventFilter(QObject *obj, QEvent *event) override;
+    void dragEnterEvent(QDragEnterEvent *event) override;
+    void dropEvent(QDropEvent *event) override;
     virtual QString defaultParameter() = 0;
     QPoint dragStartPosition;
     Trace *dragTrace;
     Ui::TraceWidget *ui;
     TraceModel &model;
     int createCount;
+
+private:
+    QString dropFilename;
+    // These can optionally be applied when importing an s2p file
+    Calibration *cal;
+    Deembedding *deembed;
 };
 
 #endif // TRACEWIDGET_H
diff --git a/Software/PC_Application/LibreVNA-GUI/VNA/tracewidgetvna.cpp b/Software/PC_Application/LibreVNA-GUI/VNA/tracewidgetvna.cpp
index a7766d2..6327e5c 100644
--- a/Software/PC_Application/LibreVNA-GUI/VNA/tracewidgetvna.cpp
+++ b/Software/PC_Application/LibreVNA-GUI/VNA/tracewidgetvna.cpp
@@ -4,17 +4,13 @@
 #include "Traces/tracetouchstoneexport.h"
 #include "Traces/tracecsvexport.h"
 #include "ui_tracewidget.h"
-#include "ui_s2pImportOptions.h"
-#include "CustomWidgets/informationbox.h"
 #include "appwindow.h"
 
 #include <QFileDialog>
 #include <QMenu>
 
-TraceWidgetVNA::TraceWidgetVNA(TraceModel &model, Calibration &cal, Deembedding &deembed, QWidget *parent)
-    : TraceWidget(model, parent),
-      cal(cal),
-      deembed(deembed)
+TraceWidgetVNA::TraceWidgetVNA(TraceModel &model, Calibration *cal, Deembedding *deembed, QWidget *parent)
+    : TraceWidget(model, cal, deembed, parent)
 {
     auto exportMenu = new QMenu();
     auto exportTouchstoneAction = new QAction("Touchstone");
@@ -54,84 +50,3 @@ void TraceWidgetVNA::exportTouchstone()
     }
 }
 
-void TraceWidgetVNA::importDialog()
-{
-    auto filename = QFileDialog::getOpenFileName(nullptr, "Open measurement file", "", "Touchstone files (*.s1p *.s2p *.s3p *.s4p);;CSV files (*.csv)", nullptr, Preferences::QFileDialogOptions());
-    if (!filename.isEmpty()) {
-        try {
-            std::vector<Trace*> traces;
-            int touchstonePorts = 0;
-            QString prefix = QString();
-            if(filename.endsWith(".csv")) {
-                auto csv = CSV::fromFile(filename);
-                traces = Trace::createFromCSV(csv);
-            } else {
-                // must be a touchstone file
-                auto t = Touchstone::fromFile(filename.toStdString());
-                traces = Trace::createFromTouchstone(t);
-                touchstonePorts = t.ports();
-            }
-            // contruct prefix from filename
-            prefix = filename;
-            // remove any directory names (keep only the filename itself)
-            int lastSlash = qMax(prefix.lastIndexOf('/'), prefix.lastIndexOf('\\'));
-            if(lastSlash != -1) {
-                prefix.remove(0, lastSlash + 1);
-            }
-            // remove file type
-            prefix.truncate(prefix.indexOf('.'));
-            prefix.append("_");
-            auto i = new TraceImportDialog(model, traces, prefix);
-            if(AppWindow::showGUI()) {
-                i->show();
-            }
-            // potential candidate to process via calibration/de-embedding
-            connect(i, &TraceImportDialog::importFinsished, [=](const std::vector<Trace*> &traces) {
-                if(traces.size() == touchstonePorts*touchstonePorts) {
-                    // all traces imported, can calculate calibration/de-embedding
-                    bool calAvailable = cal.getNumPoints() > 0;
-                    bool deembedAvailable = deembed.getOptions().size() > 0;
-                    if(calAvailable || deembedAvailable) {
-                        // check if user wants to apply either one to the imported traces
-                        auto dialog = new QDialog();
-                        auto ui = new Ui::s2pImportOptions;
-                        ui->setupUi(dialog);
-                        connect(dialog, &QDialog::finished, [=](){
-                            delete ui;
-                        });
-                        ui->applyCal->setEnabled(calAvailable);
-                        ui->deembed->setEnabled(deembedAvailable);
-                        bool applyCal = false;
-                        bool applyDeembed = false;
-                        connect(ui->applyCal, &QCheckBox::toggled, [&](bool checked) {
-                            applyCal = checked;
-                        });
-                        connect(ui->deembed, &QCheckBox::toggled, [&](bool checked) {
-                            applyDeembed = checked;
-                        });
-                        if(AppWindow::showGUI()) {
-                            dialog->exec();
-                        }
-                        // assemble trace set
-                        std::map<QString, Trace*> set;
-                        for(int i=1;i<=touchstonePorts;i++) {
-                            for(int j=1;j<=touchstonePorts;j++) {
-                                QString name = "S"+QString::number(i)+QString::number(j);
-                                int index = (i-1)*touchstonePorts+(j-1);
-                                set[name] = traces[index];
-                            }
-                        }
-                        if(applyCal) {
-                                cal.correctTraces(set);
-                        }
-                        if(applyDeembed) {
-                            deembed.Deembed(set);
-                        }
-                    }
-                }
-            });
-        } catch(const std::exception& e) {
-            InformationBox::ShowError("Failed to import file", QString("Attempt to import file ended with error: \"") + e.what()+"\"");
-        }
-    }
-}
diff --git a/Software/PC_Application/LibreVNA-GUI/VNA/tracewidgetvna.h b/Software/PC_Application/LibreVNA-GUI/VNA/tracewidgetvna.h
index 77b5039..32a5599 100644
--- a/Software/PC_Application/LibreVNA-GUI/VNA/tracewidgetvna.h
+++ b/Software/PC_Application/LibreVNA-GUI/VNA/tracewidgetvna.h
@@ -8,18 +8,15 @@
 class TraceWidgetVNA : public TraceWidget
 {
 public:
-    TraceWidgetVNA(TraceModel &model, Calibration &cal, Deembedding &deembed, QWidget *parent = nullptr);
+    TraceWidgetVNA(TraceModel &model, Calibration *cal, Deembedding *deembed, QWidget *parent = nullptr);
 public slots:
     void exportCSV();
     void exportTouchstone();
     virtual void exportDialog() override {}
-    virtual void importDialog() override;
+    virtual QStringList supportsImportFileFormats() override {return {"csv", "s1p", "s2p", "s3p", "s4p"};}
 
 protected:
     virtual QString defaultParameter() override {return "S11";}
-    // These can optionally be applied when importing an s2p file
-    Calibration &cal;
-    Deembedding &deembed;
 };
 
 #endif // TRACEWIDGETVNA_H
diff --git a/Software/PC_Application/LibreVNA-GUI/VNA/vna.cpp b/Software/PC_Application/LibreVNA-GUI/VNA/vna.cpp
index c7e64d3..c39d2ad 100644
--- a/Software/PC_Application/LibreVNA-GUI/VNA/vna.cpp
+++ b/Software/PC_Application/LibreVNA-GUI/VNA/vna.cpp
@@ -596,7 +596,7 @@ VNA::VNA(AppWindow *window, QString name)
     markerModel = new MarkerModel(traceModel, this);
 
     auto tracesDock = new QDockWidget("Traces");
-    traceWidget = new TraceWidgetVNA(traceModel, cal, deembedding);
+    traceWidget = new TraceWidgetVNA(traceModel, &cal, &deembedding);
     tracesDock->setWidget(traceWidget);
     window->addDockWidget(Qt::LeftDockWidgetArea, tracesDock);
     docks.insert(tracesDock);