ENH: add a deprecation status label for deprecated applications in QtWidgetMainWindow

Modules/Wrappers/QtWidget/src/appmainwindow.ui

@@ -34,6 +34,13 @@
     <property name="bottomMargin">
      <number>12</number>
     </property>
+    <item alignment="Qt::AlignHCenter|Qt::AlignVCenter">
+     <widget class="QLabel" name="deprecation">
+      <property name="text">
+       <string>Deprecation status</string>
+      </property>
+     </widget>
+    </item>
     <item>
      <widget class="QTabWidget" name="tabWidget">
       <property name="currentIndex">

Modules/Wrappers/QtWidget/src/otbWrapperQtWidgetMainWindow.cxx

@@ -70,6 +70,18 @@ QtMainWindow::QtMainWindow(Application::Pointer app, QtWidgetView* gui, QWidget*
   // Setup the progress bar to observe the model
   ui->progressBar->SetModel(gui->GetModel());
 
+  // Fill and display the deprecation status label if needed, or hide it.
+  if (app->IsDeprecated())
+  {
+    ui->deprecation->setVisible(true);
+    ui->deprecation->setText("<font color='red'>This application is deprecated and will be removed in a future release.</font>");
+  }
+  else
+  {
+    ui->deprecation->setVisible(false);
+    ui->deprecation->setText("");
+  }
+
   // Connect application progress text to the QLabel
   connect(ui->progressBar, &QtWidgetSimpleProgressReport::SetText, ui->message, &QLabel::setText);