Don't allow multiple imports at once

src/importer/importer.py

@@ -91,6 +91,8 @@ class Importer(ErrorProducer):
     def run(self):
         """Use several Gio.Task to import games from added sources"""
 
+        shared.win.get_application().lookup_action("import").set_enabled(False)
+
         self.create_dialog()
 
         # Collect all errors and reset the cancellables for the managers
@@ -221,6 +223,7 @@ class Importer(ErrorProducer):
         self.import_dialog.close()
         self.summary_toast = self.create_summary_toast()
         self.create_error_dialog()
+        shared.win.get_application().lookup_action("import").set_enabled(True)
 
     def create_error_dialog(self):
         """Dialog containing all errors raised by importers"""