Fix crash when reloading folder

imageringlist.cpp

@@ -71,6 +71,12 @@ ImageRingList::ImageRingList(QObject *parent) : QObject(parent)
     connect(&m_fileSystemWatcher, SIGNAL(directoryChanged(QString)), this, SLOT(dirChanged(QString)));
 }
 
+ImageRingList::~ImageRingList()
+{
+    QThreadPool::globalInstance()->clear();
+    QThreadPool::globalInstance()->waitForDone();
+}
+
 bool ImageRingList::setDir(const QString path, const QString &currentFile)
 {
     QDir dir(path);