Merge pull request #5054 from nyalldawson/canvas_select

Ensure canvas has focus if nothing else has

src/app/qgisapp.cpp

@@ -1234,6 +1234,7 @@ QgisApp::QgisApp( QSplashScreen *splash, bool restorePlugins, bool skipVersionCh
   }
 #endif
 
+  connect( qApp, &QApplication::focusChanged, this, &QgisApp::onFocusChanged );
 } // QgisApp ctor
 
 QgisApp::QgisApp()
@@ -8791,6 +8792,16 @@ void QgisApp::userRotation()
   mMapCanvas->refresh();
 }
 
+void QgisApp::onFocusChanged( QWidget *oldWidget, QWidget *newWidget )
+{
+  Q_UNUSED( oldWidget );
+  // If nothing has focus even though this window is active, ensure map canvas receives it
+  if ( !newWidget && isActiveWindow() )
+  {
+    mapCanvas()->setFocus();
+  }
+}
+
 // toggle overview status
 void QgisApp::isInOverview()
 {

src/app/qgisapp.h

@@ -1510,6 +1510,8 @@ class APP_EXPORT QgisApp : public QMainWindow, private Ui::MainWindow
 
     void updateCrsStatusBar();
 
+    void onFocusChanged( QWidget *oldWidget, QWidget *newWidget );
+
   signals:
 
     /**