Fix empty editor windows (#7515)

Fix the problem with empty windows as described in issue #7412.

The `refocus` method in `MainWindow` is made public so that it can be called from `Editor::closeEvent`. It has also been refactored for better readability.

---------

Co-authored-by: Michael Gregorius <michael.gregorius.git@arcor.de>
Co-authored-by: Dalton Messmer <messmer.dalton@gmail.com>

src/gui/MainWindow.cpp

@@ -975,26 +975,21 @@ void MainWindow::toggleFullscreen()
  */
 void MainWindow::refocus()
 {
-	QList<QWidget*> editors;
-	editors
-		<< getGUI()->songEditor()->parentWidget()
-		<< getGUI()->patternEditor()->parentWidget()
-		<< getGUI()->pianoRoll()->parentWidget()
-		<< getGUI()->automationEditor()->parentWidget();
+	const auto gui = getGUI();
 
-	bool found = false;
-	QList<QWidget*>::Iterator editor;
-	for( editor = editors.begin(); editor != editors.end(); ++editor )
+	// Attempt to set the focus on the first of these editors that is not hidden...
+	for (auto editorParent : { gui->songEditor()->parentWidget(), gui->patternEditor()->parentWidget(),
+		gui->pianoRoll()->parentWidget(), gui->automationEditor()->parentWidget() })
 	{
-		if( ! (*editor)->isHidden() ) {
-			(*editor)->setFocus();
-			found = true;
-			break;
+		if (!editorParent->isHidden())
+		{
+			editorParent->setFocus();
+			return;
 		}
 	}
 
-	if( ! found )
-		this->setFocus();
+	// ... otherwise set the focus on the main window.
+	this->setFocus();
 }
 
 

src/gui/editors/Editor.cpp

@@ -24,6 +24,8 @@
 
 #include "Editor.h"
 
+#include "GuiApplication.h"
+#include "MainWindow.h"
 #include "Song.h"
 
 #include "embed.h"
@@ -138,7 +140,7 @@ QAction *Editor::playAction() const
 	return m_playAction;
 }
 
-void Editor::closeEvent( QCloseEvent * _ce )
+void Editor::closeEvent(QCloseEvent * event)
 {
 	if( parentWidget() )
 	{
@@ -148,7 +150,8 @@ void Editor::closeEvent( QCloseEvent * _ce )
 	{
 		hide();
 	}
-	_ce->accept();
+	getGUI()->mainWindow()->refocus();
+	event->ignore();
  }
 
 DropToolBar::DropToolBar(QWidget* parent) : QToolBar(parent)