We can copy in html page

src/ksieveui/editor/sieveeditorhelphtmlwidget.cpp

@@ -106,6 +106,11 @@ void SieveEditorHelpHtmlWidget::zoomIn()
     mWebView->setZoomFactor(mZoomFactor / 100.0);
 }
 
+void SieveEditorHelpHtmlWidget::copy()
+{
+    mWebView->triggerPageAction(QWebEnginePage::Copy);
+}
+
 void SieveEditorHelpHtmlWidget::zoomOut()
 {
     if (mZoomFactor <= 10) {

src/ksieveui/editor/sieveeditorhelphtmlwidget.h

@@ -41,6 +41,7 @@ public:
     void resetZoom();
     void zoomOut();
     void zoomIn();
+    void copy();
 
 Q_SIGNALS:
     void titleChanged(KSieveUi::SieveEditorHelpHtmlWidget *widget, const QString &title);

src/ksieveui/editor/sieveeditortextmodewidget.cpp

@@ -275,7 +275,12 @@ void SieveEditorTextModeWidget::cut()
 
 void SieveEditorTextModeWidget::copy()
 {
-    mTextEdit->copy();
+    QWidget *w = mTabWidget->currentWidget();
+    if (w == mTextEdit) {
+        mTextEdit->copy();
+    } else if (SieveEditorHelpHtmlWidget *page = qobject_cast<SieveEditorHelpHtmlWidget *>(w)) {
+        page->copy();
+    }
 }
 
 void SieveEditorTextModeWidget::selectAll()