How can I create a single Tkinter Listbox with line breaks?

Question

I have a work object Tkinter.Listbox, but I want to configure it so that its elements can have a carriage return without the need to somehow configure several related elements.

For example, if I want to create a selection bar with elements that look like this.

    # Here are four elements for the selector Listbox..
lb_items = ('mama', 'luigi', 'my birds', \
            'this is a single element\n spanning two lines!')
    # This generates and displays the selector window..
tk_selector = SingleSelect(lb_items, "TEST SELECTOR")
tk_selector.run_selector()

.. it would be great if I could get an output similar to this layout.

.. instead of what it actually generates, that is ..

Listboxes seem to ignore strings '\n'and triple quotes with string returns; if used \n, neither characters nor line breaks are displayed.

Is it possible to have separate, selectable list items that appear with line breaks?

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Answer 1

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---

class Multiline_Single_Selector(object):
      ## Go ahead and choose a better class name than this, too. :/
    def __init__(self, itemlist, ..):
              # ..
        lb_splitlines = self._parse_strings(itemlist) 
          # ^ splits the raw strings and records their indices.
          #  returns the split strings as a list of Listbox elements.
        self.my_Listbox.insert(0, *lb_splitlines) 
          # ^ put the converted strings into the Listbox..

        self.my_Listbox.bind('<<ListboxSelect>>', self._reselect)
          # ^ Whenever the Listbox selection is modifed, it triggers the
          #  <<ListboxSelect>> event. Bind _reselect to it to determine
          #  which lines ought to be highlighted when the selection updates.
              # ..

    def _parse_strings(self, string_list):
        '''Accepts a list of strings and breaks each string into a series of lines,
logs the sets, and stores them in the item_roster and string_register attributes.
Returns the split strings to be inserted into a Listbox.'''

        self.index_sets = index_sets = []
          # ^ Each element in this list is a tuple containing the first and last
          #  Listbox element indices for a set of lines. 

        self.string_register = register = {}
          # ^ A dict with a whole string element keyed to the index of the its
          #  first element in the Listbox.

        all_lines = [] 
          # ^ A list of every Listbox element. When a string is broken into lines,
          #  the lines go in here.

        line_number = 0
        for item in string_list: 
            lines = item.splitlines()

            all_lines.extend(lines) # add the divided string to the string stack
            register[line_number] = item
                # ^ Saves this item keyed to the first Listbox element it associated
                #  with. If the item is selected when the Listbox closes, the original 
                #  (whole) string is found and returned based on this index number.

            qty = len(lines)
            if qty == 1: # single line item..
                index_sets.append((line_number, line_number))
            else: # multiple lines in this item..
                element_range = line_number, line_number + qty - 1 
                  # ^ the range of Listbox indices..
                index_sets.extend([element_range] * qty) 
                  # ^ ..one for each element in the Listbox.

            line_number += qty # increment the line number.
        return all_lines

    def _reselect(self, event=None):
        "Called whenever the Listbox selection changes."
        selection = self.my_Listbox.curselection() # Get the new selection data.
        if not selection: # if there is nothing selected, do nothing.
            return

        lines_st, lines_ed = self.index_sets[selection[0]]
            # ^ Get the string block associated with the current selection.
        self.my_Listbox.selection_set(lines_st, lines_ed) 
            # ^ select all lines associated with the original string.

    def _recall(self, event=None):
        "Get the complete string for the currently selected item."
        selection = self.my_Listbox.curselection()
        if selection: # an item is selected!
            return self.string_register[selection[0]]
        return None   # no item is selected.

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Answer 2

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