Focus the message input when the chat window is activated

tools/chatgui/src/mainwindow.cpp

@@ -1361,6 +1361,26 @@ void MainWindow::showIncomingMessageNotification(const QString& target, quint64
     m_messageNotification->showMessage(target, m_db->getDisplayName(author), channel, m_trayIcon->geometry(), screen());
 }
 
+void MainWindow::changeEvent(QEvent* event) {
+    QMainWindow::changeEvent(event);
+    if (event->type() != QEvent::ActivationChange || !isActiveWindow()) return;
+    QTimer::singleShot(0, this, [this] {
+        auto* input = m_messageList ? m_messageList->focusProxy() : nullptr;
+        const bool ready = input && input->isVisible() && input->isEnabled();
+        if (QApplication::activeWindow() != this || !isVisible() || isMinimized() ||
+            QApplication::activeModalWidget() || QApplication::activePopupWidget() || !ready) {
+            GUI_DEBUG("window activation: input focus skipped active=%d visible=%d minimized=%d modal=%d popup=%d input_ready=%d",
+                      QApplication::activeWindow() == this, isVisible(), isMinimized(), bool(QApplication::activeModalWidget()),
+                      bool(QApplication::activePopupWidget()), ready);
+            return;
+        }
+        m_messageList->setFocus(Qt::ActiveWindowFocusReason);
+        auto* focused = QApplication::focusWidget();
+        GUI_DEBUG("window activation: message input focused target=%s focus_widget=%s", qPrintable(m_currentChannelId),
+                  focused ? focused->metaObject()->className() : "none");
+    });
+}
+
 void MainWindow::closeEvent(QCloseEvent *event) {
     DEBUG_DEBUG(DEBUG_CATEGORY_GENERAL, "MainWindow: closeEvent — hiding to tray");
     saveWindowGeometry();