title: Select multiple entries in Tkinter treeview without pressing ctrl key
body: <p>I am trying to select multiple entries from Tkinter treeview. I used <strong>selectmode = extended</strong> for the same(use ctrl+enter key). But as soon as I try to open new branch in the tree(ctrl pressed), I am not able to open and if I do the same without pressing ctrl my selections from branch 1 disappears.</p>
  
  <p>Hence, I am trying to get some other way for selecting multiple nodes from Tkinter tree (from different brances) without pressing ctrl key. (i.e either remembering my mouse selections or some checkbox or any other suggestion)</p>
  
  <ul>
  <li>Here is a working code example which works for multiple selection in different branches using ctrl key but I need multiple selection for selecting nodes in different branches without pressing ctrl as using this I am not able to open new branch after selecting first one and if released nodes opens but choices disappears.</li>
  </ul>
  
  <p>code:</p>
  
  <pre><code>import ttk
  import Tkinter as tk
  
  def select():
      for i in tree.selection():
          item_iid = i
          print "".join([str(tree.item(i)['text'])])# for i in curItems])
  
  
  root = tk.Tk()
  tree = ttk.Treeview(root,show="tree")#, selectmode=EXTENDED)  
  tree.config(columns=("col1"))
  
  #SUb treeview
  style = ttk.Style(root)
  style.configure("Treeview")
  tree.configure(style="Treeview")
  
  tree.insert("", "0", "item1", text="Branch1",)
  tree.insert("", "1", "item2", text="Branch2")
  
  #sub tree using item attribute to achieve that
  tree.insert("item1", "1", text="FRED")
  tree.insert("item1", "1", text="MAVIS")
  tree.insert("item1", "1", text="BRIGHT")
  
  tree.insert("item2", "2", text="SOME")
  tree.insert("item2", "2", text="NODES")
  tree.insert("item2", "2", text="HERE")
  
  tree.pack(fill=tk.BOTH, expand=True)
  tree.bind("&lt;Return&gt;", lambda e: select()) 
  
  root.mainloop()
  </code></pre>
  
  <p><strong>Expected:</strong> Select multiple nodes from different branches without pressing ctrl key</p>