Allow dunder to prevent recursion

TermTk/TTkWidgets/splitter.py

@@ -51,10 +51,10 @@ class TTkSplitter(TTkFrame):
         self._splitterInitialized = True
 
         class _SplitterLayout(TTkLayout):
-            @staticmethod
+            # Use dunder instead of 'self' in non-static methods to avoid
+            # recursion.
             def insertWidget(_, index, widget):
                 self.insertWidget(index, widget)
-            @staticmethod
             def addWidget(_, widget):
                 self.addWidget(widget)
         self.setLayout(_SplitterLayout())