Question

I have a wx.ListBox that I would like the user to select from as if they were holding down the CTRL key. So – if you click on an item that is not selected, it will be selected (without modifying other selections), and if you click on a selected item, it will be deselected (again without modifying other selections).

The code to create the listbox is:

    self.myListBox = wx.ListBox(self,
                                    -1,
                                    choices=self.keys,
                                    style =  wx.LB_HSCROLL
                                           | wx.LB_MULTIPLE
                                           | wx.LB_NEEDED_SB
                                           | wx.LB_SORT)
    self.Bind(wx.EVT_LISTBOX, self.OnSelection, self.myListBox)

Problems / questions:

• Is there already an easy way to do this? Either wx.LB_MULTIPLE or wx.LB_EXTENDED look like they might be what I want, but I’ve tried both and it doesn’t appear to change anything. The description in the documentation is a little vague as well – what exactly is the difference between the two?

• I know can get the id of the selected item with event.GetSelection(), but if I try to implement the above logic, i.e.:

  if self.myListBox.IsSelected(idx):
      self.myListBox.Deselect(idx)
  else:
      self.myListBox.Select(idx)
  

  the event has already fired and so it just deselects whatever was just selected. Tried calling event.Skip() before that as well, but no luck there either. Is there a way I can stop it from doing that?

• I noticed that when dragging the mouse for multiple selections event.GetSelection() would get the correct id’s going up – i.e., 3, 2, 1, 0 – but going down it would only show the first – 0, 0, 0, 0. I’m guessing it’s just printing out the first item in the list of selections — is there a way to get the list from the event object (as opposed to calling self.myListBox.GetSelections())?

I’m running Linux and wxPython version 2.6.4.0.

Answer 1

(Late answer, but it might be of use to document.)
I ended up writing handlers for the onClick events:

def OnSelection(self, event):
    """Simulate CTRL-click"""
    selection = self.myListBox.GetSelections()

    for i in selection:
        if i not in self.selectedItems:
            # add to list of selected items
            self.selectedItems.append(i)
            self.myListBox.Select(i)
        elif len(selection) == 1:
            # remove from list of selected items
            self.selectedItems.remove(i)
            self.myListBox.Deselect(i)

    for i in self.selectedItems:
        # actually select all the items in the list
        self.myListBox.Select(i)