Fix crash when re-opening VST effect manage dialog

Unset Qt::WA_DeleteOnClose for the dialog to avoid deletion when closed

Author: PhysSong

plugins/VstEffect/VstEffectControls.cpp

@@ -317,7 +317,7 @@ manageVSTEffectView::manageVSTEffectView( VstEffect * _eff, VstEffectControls *
 	m_vi->m_subWindow->setWidget(m_vi->m_scrollArea);
 	m_vi->m_subWindow->setWindowTitle( _eff->m_plugin->name() + tr( " - VST parameter control" ) );
 	m_vi->m_subWindow->setWindowIcon( PLUGIN_NAME::getIconPixmap( "logo" ) );
-	//m_vi->m_subWindow->setAttribute(Qt::WA_DeleteOnClose);
+	m_vi->m_subWindow->setAttribute(Qt::WA_DeleteOnClose, false);
 
 
 	l->setContentsMargins( 20, 10, 10, 10 );