mainwindow: Specify the drop handler plugin group

Author: ales-erjavec

Orange/canvas/mainwindow.py

@@ -3,6 +3,7 @@
     QFormLayout, QCheckBox, QLineEdit, QWidget, QVBoxLayout, QLabel
 )
 from orangecanvas.application.settings import UserSettingsDialog, FormLayout
+from orangecanvas.document.interactions import PluginDropHandler
 from orangecanvas.document.usagestatistics import UsageStatistics
 from orangecanvas.utils.overlay import NotificationOverlay
 
@@ -107,6 +108,9 @@ def __init__(self, *args, **kwargs):
         super().__init__(*args, **kwargs)
         self.notification_overlay = NotificationOverlay(self.scheme_widget)
         self.notification_server = None
+        self.scheme_widget.setDropHandlers([
+            PluginDropHandler("orange.canvas.drophandler")
+        ])
 
     def open_canvas_settings(self):
         # type: () -> None

setup.py

@@ -97,7 +97,7 @@
     "orange.canvas.help": (
         "html-index = Orange.widgets:WIDGET_HELP_PATH",
     ),
-    "orangecanvas.document.interactions.DropHandler": (
+    "orange.canvas.drophandler": (
         "File = Orange.widgets.data.owfile:OWFileDropHandler",
         "Load Model = Orange.widgets.model.owloadmodel:OWLoadModelDropHandler",
         "Distance File = Orange.widgets.unsupervised.owdistancefile:OWDistanceFileDropHandler",