patch QApplication in order to distinguish settings of instances

use  ~/.config/nicos_<instrument> instead of common ~/.config/nicos

nicosman.py

@@ -261,6 +261,17 @@ class NicosManager(ServiceManager):
 
     def do_gui(self, ins):
         self.prepare_client(ins)
+
+        # patch QApplication to use 'nicos_<instr>' instead of 'nicos' as organizationName
+        # for different settings and log files
+        import nicos.guisupport.qt
+
+        class QApplication(nicos.guisupport.qt.QApplication):
+            def __init__(self, *args, organizationName=None, **kwds):
+                super().__init__(*args, organizationName=f'nicos_{ins}', **kwds)
+
+        nicos.guisupport.qt.QApplication = QApplication
+
         from nicos.clients.gui.main import main
         print('starting nicos gui %s' % ins)
         try: