fix: potential bug related to widgets in PyVistaBackendInterface class (#433)

Co-authored-by: pyansys-ci-bot <[email protected]>

Author: moe-ad

doc/changelog.d/433.miscellaneous.md

@@ -0,0 +1 @@
+Fix: potential bug related to widgets in \`PyVistaBackendInterface\` class

src/ansys/tools/visualization_interface/backends/pyvista/pyvista.py

@@ -225,7 +225,8 @@ def add_widget(self, widget: Union[PlotterWidget, List[PlotterWidget]]):
         """
         if isinstance(widget, list):
             self._widgets.extend(widget)
-            widget.update()
+            for w in widget:
+                w.update()
         else:
             self._widgets.append(widget)
             widget.update()