spectra: do not send selection_changed on the same selection

orangecontrib/spectroscopy/widgets/owspectra.py

@@ -1322,6 +1322,8 @@ def current_selection():
 
         old_sel_ci = current_selection()
 
+        changed = False
+
         if add_to_group:  # both keys - need to test it before add_group
             selnum = np.max(self.selection_group)
         elif add_group:
@@ -1331,15 +1333,20 @@ def current_selection():
         else:
             # remove the current selection
             redraw_curve_indices.update(old_sel_ci)
-            self.selection_group *= 0  # remove
+            if np.any(self.selection_group):
+                self.selection_group *= 0  # remove
+                changed = True
             selnum = 1
         # add new
         if data_indices is not None:
             self.selection_group[data_indices] = selnum
             redraw_curve_indices.update(
                 icurve for idata, icurve in invd.items() if idata in data_indices_set)
+            changed = True
 
         fixes = self.make_selection_valid()
+        if fixes:
+            changed = True
         redraw_curve_indices.update(
             icurve for idata, icurve in invd.items() if idata in fixes)
 
@@ -1351,7 +1358,8 @@ def current_selection():
             redraw_curve_indices.update(old_sel_ci)
 
         self.set_curve_pens(redraw_curve_indices)
-        self.selection_changed_confirm()
+        if changed:
+            self.selection_changed_confirm()
 
     def make_selection_valid(self):
         """ Make the selection valid and return the changed positions. """