single pixel to reset subset selection

without having to inherit from InteractCheckableTool or BqplotSelectionTool since those would require self.interact

jdaviz/core/tools.py

@@ -282,6 +282,12 @@ class SinglePixelRegion(CheckableTool):
     tool_tip = 'Define a single-pixel spatial region of interest'
 
     def activate(self):
+        # This is copied from glue-jupyter's BqplotSelectionTool (but we don't inherit
+        # from that because that in turn inherits from InteractCheckableTool which requires
+        # setting self.interact)
+        if self.viewer.session.application.get_setting('new_subset_on_selection_tool_change'):
+            self.viewer.session.edit_subset_mode.edit_subset = None
+
         self.viewer.add_event_callback(self.on_mouse_event, events=['click'])
 
     def deactivate(self):