Я создал дерево внутри Canvas, и я также позволил MouseWheel прокручивать вверх и вниз.

Однако как предотвратить прокрутку, если содержимое дерева не превышает размер холста? (Содержимое дерева может быть больше размера холста при расширении)

Пожалуйста, запустите следующий код:

from Tkinter import Tk, Frame, BOTH, Canvas
from xml.dom.minidom import parseString
from idlelib.TreeWidget import TreeItem, TreeNode

class DomTreeItem(TreeItem):
   def __init__(self, node):
      self.node = node
   def GetText(self):
      node = self.node
      if node.nodeType == node.ELEMENT_NODE:
         return node.nodeName
      elif node.nodeType == node.TEXT_NODE:
         return node.nodeValue
   def IsExpandable(self):
      node = self.node
      return node.hasChildNodes()
   def GetSubList(self):
      parent = self.node
      children = parent.childNodes
      prelist = [DomTreeItem(node) for node in children]
      itemlist = [item for item in prelist if item.GetText().strip()]
      return itemlist

data = '''
<top>
 <b>
  <c>d</c>
  <c>e</c>
 </b>
 <b>
  <c><c><c><c><c>f</c></c></c></c></c>
  <c><c><c><c><c>f</c></c></c></c></c>
  <c><c><c><c><c>f</c></c></c></c></c>
 </b>
</top>
'''

class Application(Frame):
   def __init__(self, parent):
      Frame.__init__(self, parent, background = "white")
      parent.configure(bg = "black")
      self.pack(fill = BOTH, expand = True, padx = 20, pady = 20)      
      self.parent = parent

      self.parent.geometry('%dx%d+%d+%d' % (700, 700, 0, 0))

      self.canvas = Canvas(self, bg = "white", bd = 10, highlightbackground = "black")
      self.canvas.grid(column = 0, row = 0, rowspan = 2)
      dom = parseString(data)
      item = DomTreeItem(dom.documentElement)
      node = TreeNode(self.canvas, None, item)
      node.update()
      node.expand()

      self.parent.bind("<MouseWheel>", self.mouse_wheel) # Windows mouse wheel event
      self.parent.bind("<Button-4>", self.mouse_wheel) # Linux mouse wheel event (Up)
      self.parent.bind("<Button-5>", self.mouse_wheel) # Linux mouse wheel event (Down)

   def mouse_wheel(self, event):
      """ Mouse wheel as scroll bar """
      direction = 0
      # respond to Linux or Windows wheel event
      if event.num == 5 or event.delta == -120:
         direction = 1
      if event.num == 4 or event.delta == 120:
         direction = -1
      self.canvas.yview_scroll(direction, "units")

def main():
   root = Tk()
   Application(root)
   root.mainloop()

if __name__ == '__main__':
   main()