gh-157762: Fix Alt-2 zoom height binding in IDLE tree windows

Author: lazerg

Lib/idlelib/idle_test/test_tree.py

@@ -28,6 +28,10 @@ def test_init(self):
         node = tree.TreeNode(sc.canvas, None, item)
         node.expand()
 
+    def test_zoom_height(self):
+        sc = tree.ScrolledCanvas(self.root)
+        self.assertEqual(sc.zoom_height(None), "break")
+
 
 if __name__ == '__main__':
     unittest.main(verbosity=2)

Lib/idlelib/tree.py

@@ -423,6 +423,7 @@ def __init__(self, master, **opts):
         if 'yscrollincrement' not in opts:
             opts['yscrollincrement'] = 17
         self.master = master
+        self.top = master.winfo_toplevel()
         self.frame = Frame(master)
         self.frame.rowconfigure(0, weight=1)
         self.frame.columnconfigure(0, weight=1)
@@ -457,7 +458,7 @@ def unit_down(self, event):
         self.canvas.yview_scroll(1, "unit")
         return "break"
     def zoom_height(self, event):
-        zoomheight.zoom_height(self.master)
+        zoomheight.ZoomHeight(self).zoom_height()
         return "break"
 
 

Misc/NEWS.d/next/IDLE/2026-09-19-10-30-00.gh-issue-157762.Kv7pQ2.rst

@@ -0,0 +1,3 @@
+Fix the Alt-2 (zoom height) binding in IDLE's tree windows, such as Path
+Browser and Module Browser.  It called a function removed from
+``idlelib.zoomheight`` in 2019 and raised :exc:`AttributeError`.