Issue #25313: Change the handling of new built-in text color themes to better

address the compatibility problem introduced by the addition of IDLE Dark.
Consistently use the revised idleConf.CurrentTheme everywhere in idlelib.

Lib/idlelib/TreeWidget.py

@@ -249,7 +249,7 @@ class TreeNode:
         except AttributeError:
             # padding carefully selected (on Windows) to match Entry widget:
             self.label = Label(self.canvas, text=text, bd=0, padx=2, pady=2)
-        theme = idleConf.GetOption('main','Theme','name')
+        theme = idleConf.CurrentTheme()
         if self.selected:
             self.label.configure(idleConf.GetHighlight(theme, 'hilite'))
         else: