Use new QFileDialog::DontUseCustomDirectoryIcons flag for faster file dialogs

In Qt 4.8.6 there's a new option QFileDialog::DontUseCustomDirectoryIcons
promising much better performance when there are many folders.

Closes #511.

src/core/sample_buffer.cpp

@@ -1,7 +1,7 @@
 /*
  * sample_buffer.cpp - container-class sampleBuffer
  *
- * Copyright (c) 2005-2010 Tobias Doerffel <tobydox/at/users.sourceforge.net>
+ * Copyright (c) 2005-2013 Tobias Doerffel <tobydox/at/users.sourceforge.net>
  *
  * This file is part of Linux MultiMedia Studio - http://lmms.sourceforge.net
  *
@@ -742,6 +742,9 @@ void sampleBuffer::visualize( QPainter & _p, const QRect & _dr,
 QString sampleBuffer::openAudioFile() const
 {
 	QFileDialog ofd( NULL, tr( "Open audio file" ) );
+#if QT_VERSION >= 0x040806
+	ofd.setOption( QFileDialog::DontUseCustomDirectoryIcons );
+#endif
 
 	QString dir;
 	if( !m_audioFile.isEmpty() )

src/core/song.cpp

@@ -1241,6 +1241,9 @@ void song::importProject()
 			" (*.h2song);;" +
 			tr("All file types") +
 			" (*.*)");
+#if QT_VERSION >= 0x040806
+	ofd.setOption( QFileDialog::DontUseCustomDirectoryIcons );
+#endif
 
 	ofd.setFileMode( QFileDialog::ExistingFiles );
 	if( ofd.exec () == QDialog::Accepted && !ofd.selectedFiles().isEmpty() )
@@ -1296,6 +1299,9 @@ void song::exportProject(bool multiExport)
 	}
 
 	QFileDialog efd( engine::mainWindow() );
+#if QT_VERSION >= 0x040806
+	efd.setOption( QFileDialog::DontUseCustomDirectoryIcons );
+#endif
 	if (multiExport)
 	{
 		efd.setFileMode( QFileDialog::Directory);

src/gui/MainWindow.cpp

@@ -688,6 +688,9 @@ void MainWindow::openProject( void )
 	{
 		QFileDialog ofd( this, tr( "Open project" ), "",
 			tr( "MultiMedia Project (*.mmp *.mmpz *.xml)" ) );
+#if QT_VERSION >= 0x040806
+		ofd.setOption( QFileDialog::DontUseCustomDirectoryIcons );
+#endif
 		ofd.setDirectory( configManager::inst()->userProjectsDir() );
 		ofd.setFileMode( QFileDialog::ExistingFiles );
 		if( ofd.exec () == QDialog::Accepted &&
@@ -751,6 +754,9 @@ bool MainWindow::saveProjectAs( void )
 	QFileDialog sfd( this, tr( "Save project" ), "",
 			tr( "MultiMedia Project (*.mmp *.mmpz);;"
 				"MultiMedia Project Template (*.mpt)" ) );
+#if QT_VERSION >= 0x040806
+	sfd.setOption( QFileDialog::DontUseCustomDirectoryIcons );
+#endif
 	sfd.setAcceptMode( QFileDialog::AcceptSave );
 	sfd.setFileMode( QFileDialog::AnyFile );
 	QString f = engine::getSong()->projectFileName();

src/gui/setup_dialog.cpp

@@ -1010,7 +1010,11 @@ void setupDialog::openWorkingDir()
 {
 	QString new_dir = QFileDialog::getExistingDirectory( this,
 					tr( "Choose LMMS working directory" ),
-							m_workingDir );
+							m_workingDir
+#if QT_VERSION >= 0x040806
+							, QFileDialog::DontUseCustomDirectoryIcons
+#endif
+					 );
 	if( new_dir != QString::null )
 	{
 		m_wdLineEdit->setText( new_dir );