Add copy function

mainwindow.cpp

@@ -11,6 +11,7 @@ MainWindow::MainWindow(QWidget *parent)
     : QMainWindow(parent)
     , ui(new Ui::MainWindow)
     , undoStack(new QUndoStack(this))
+    , Clipboard(QGuiApplication::clipboard())
 {
     ui->setupUi(this);
 
@@ -170,3 +171,14 @@ void MainWindow::on_actionopenFile_triggered()
 {
     this->loadPath();
 }
+
+void MainWindow::on_actionEditCopy_triggered()
+{
+    QWidget *focused = QApplication::focusWidget();
+    QLineEdit* lineEdit = qobject_cast<QLineEdit*>(focused);
+
+    if(lineEdit) {
+        Clipboard->setText(lineEdit->selectedText());
+    }
+}
+