Merge pull request #2820 from benma/qt_threading

fix Qt threading issue

gui/qt/__init__.py

@@ -82,6 +82,7 @@ class ElectrumGui:
         # GC-ed when windows are closed
         #network.add_jobs([DebugMem([Abstract_Wallet, SPV, Synchronizer,
         #                            ElectrumWindow], interval=5)])
+        QtCore.QCoreApplication.setAttribute(QtCore.Qt.AA_X11InitThreads)
         self.config = config
         self.daemon = daemon
         self.plugins = plugins