number of function parameter is counted correctly when setting new values

src/gui_qt/lib/pg_objects.py

@@ -380,6 +380,8 @@ class RegionItem(LinearRegionItem):
 
         self.logmode = False
         self.first = True
+        if not hasattr(self, '_bounds') and hasattr(self, '_boundingRectCache'):
+            self._bounds = self._boundingRectCache
 
     def setLogMode(self, xmode, _):
         if self.logmode == xmode: