write warning message in red

src/gui/export/export_masschroq_dialog/exportmasschroqdialog.cpp

@@ -46,6 +46,8 @@ ExportMasschroqDialog::ExportMasschroqDialog(QWidget *parent)
 
   ui->directorySelectWidget->setHidden(true);
   ui->msrunFilepathOkLabel->setHidden(true);
+  
+  ui->warningDirectoryLabel->setStyleSheet("QLabel { color : red; }");
 
 #if QT_VERSION >= 0x050000
   // Qt5 code