Fix a crash.

If call a visualization and then close the window Valentina will crash.

--HG--
branch : release

src/app/valentina/mainwindow.cpp

@@ -1913,6 +1913,7 @@ void MainWindow::CancelTool()
 
     currentScene->setFocus(Qt::OtherFocusReason);
     currentScene->clearSelection();
+    ui->view->itemClicked(nullptr); // Hide visualization to avoid a crash
 
     switch ( currentTool )
     {

src/libs/vtools/tools/vabstracttool.h

@@ -187,7 +187,7 @@ inline void VAbstractTool::AddVisualization()
     connect(scene, &VMainGraphicsScene::NewFactor, visual, &Visualization::SetFactor);
     scene->addItem(visual);
 
-    connect(visual, &Visualization::ToolTip, RECEIVER(this)[this] (const QString &toolTip) {emit ToolTip(toolTip);});
+    connect(visual, &Visualization::ToolTip, this, &VAbstractTool::ToolTip);
     vis = visual;
 }