Create a new version of paste:

#!/usr/bin/env python
# Encoding: UTF-8
"""This script launches a GUI for testing regular expressions."""

import sys
import os
import re
import sre_constants
from textwrap import dedent

try:
    import wx
    import wx.aui
    import wx.lib.anchors as anchors
except ImportError:
    print "This script requires wxPython."
    sys.exit(1)

class RegexTesterFrame(wx.Frame):
    def __init__(self):
        wx.Frame.__init__(
            self, None, -1, 'Regex tester', (100, 100),
            (1024, 768), wx.DEFAULT_FRAME_STYLE
        )
        # wx.Frame.__init__(
        #     self, None, -1, 'Regex tester', wx.DefaultPosition,
        #     wx.DefaultSize, wx.DEFAULT_FRAME_STYLE
        # )

        self.initialize_components()

        self.statusbar = self.CreateStatusBar(1, wx.ST_SIZEGRIP)
        self.statusbar.SetFieldsCount(2)
        self.statusbar.SetStatusWidths([-1, -3])
        self.statusbar.SetStatusText('Welcome to the RegEx tester!', 0)

    def initialize_components(self):
        self._mgr = wx.aui.AuiManager()
        self._mgr.SetManagedWindow(self)

        self.SetMinSize(wx.Size(800, 400))

        # Create a toolbar for the regex modifiers (flags).
        self._mgr.AddPane(
            self.create_flags_panel(),
            wx.aui.AuiPaneInfo().Name('modifiers').ToolbarPane().Top()
        )

        # Create a toolbar for the regex modifiers (flags).
        self._mgr.AddPane(
            self.create_functions_panel(),
            wx.aui.AuiPaneInfo().Name('functions').ToolbarPane().Top()
        )

        # Create the text input pane.
        self._mgr.AddPane(
            self.create_text_input_panel(),
            wx.aui.AuiPaneInfo().Name('text_input').Caption('Text input').
                CloseButton(False).Left().Layer(1).BestSize((600, 100))
        )

        # Create the regex pane.
        self._mgr.AddPane(
            self.create_regex_panel(),
            wx.aui.AuiPaneInfo().Name('regex').Caption('Regex').
                CloseButton(False).Top().BestSize((200, 100))
        )

        # Create the output pane.
        self._mgr.AddPane(
            self.create_output_panel(),
            wx.aui.AuiPaneInfo().Name('output').CloseButton(False).CenterPane().
                BestSize((200, 300))
        )

        self._mgr.Update()

        self.Bind(wx.EVT_CLOSE, self.on_close)

    def create_flags_panel(self):
        panel = wx.Panel(self, -1)

        # Create the check boxes.
        self.flag_dotall_checkbox = wx.CheckBox(panel, -1, 'DOTALL')
        self.flag_ic_checkbox = wx.CheckBox(panel, -1, 'IGNORECASE')
        self.flag_ext_checkbox = wx.CheckBox(panel, -1, 'VERBOSE')
        self.flag_multiline_checkbox = wx.CheckBox(panel, -1, 'MULTILINE')

        # Check ignore case by default.
        self.flag_ic_checkbox.SetValue(True)

        # Bind the change event to run the update function.
        for checkbox in [self.flag_dotall_checkbox, self.flag_ic_checkbox,
                         self.flag_ext_checkbox, self.flag_multiline_checkbox]:
            self.Bind(
                wx.EVT_CHECKBOX,
                self.update_output_event,
                checkbox
            )

        # Create the layout sizer.
        sizer = wx.BoxSizer()
        sizer.Add(wx.StaticText(panel, -1, 'Flags: '))
        sizer.Add(self.flag_dotall_checkbox)
        sizer.Add(self.flag_ic_checkbox)
        sizer.Add(self.flag_ext_checkbox)
        sizer.Add(self.flag_multiline_checkbox)

        # Create the outer sizer and add the inner sizer to it.
        outer_sizer = wx.BoxSizer()
        outer_sizer.Add(sizer, border=5, flag=wx.ALL)

        # Apply the outer sizer to the panel and return it.
        panel.SetSizerAndFit(outer_sizer)

        return panel

    def create_functions_panel(self):
        panel = wx.Panel(self, -1)

        # Create the radio buttons.
        self.func_search_radio = wx.RadioButton(panel, -1, 'Search')
        self.func_match_radio = wx.RadioButton(panel, -1, 'Match')
        self.func_findall_radio = wx.RadioButton(panel, -1, 'Find all')

        # Check the search function radio button by default.
        self.func_search_radio.SetValue(True)

        # Bind the radio buttons' change events to update the output.
        for radio in [self.func_search_radio, self.func_match_radio,
                      self.func_findall_radio]:
            self.Bind(wx.EVT_RADIOBUTTON, self.update_output_event, radio)

        # Add the radio buttons to the sizer.
        sizer = wx.BoxSizer(wx.HORIZONTAL)
        sizer.Add(wx.StaticText(panel, -1, 'Function: '))
        sizer.AddMany([
            self.func_search_radio,
            self.func_match_radio,
            self.func_findall_radio
        ])

        # Create the outer sizer and add the inner sizer to it.
        outer_sizer = wx.BoxSizer()
        outer_sizer.Add(sizer, border=5, flag=wx.ALL)

        panel.SetSizerAndFit(outer_sizer)

        return panel

    def create_regex_panel(self):
        panel = wx.Panel(self)
        self.regex_textbox = wx.TextCtrl(
            panel, style=wx.NO_BORDER | wx.TE_MULTILINE
        )

        sizer = wx.BoxSizer()
        sizer.Add(self.regex_textbox, proportion=1, flag=wx.EXPAND)

        panel.SetSizerAndFit(sizer)

        # Bind the text change event.
        self.Bind(
            wx.EVT_TEXT,
            self.update_output_event,
            self.regex_textbox
        )

        return panel

    def create_text_input_panel(self):
        panel = wx.Panel(self)
        self.input_textbox = wx.TextCtrl(
            panel, style=wx.NO_BORDER | wx.TE_MULTILINE | wx.TE_DONTWRAP | wx.HSCROLL
        )

        sizer = wx.BoxSizer()
        sizer.Add(self.input_textbox, proportion=1, flag=wx.EXPAND)

        panel.SetSizerAndFit(sizer)

        # Bind the text change event.
        self.Bind(
            wx.EVT_TEXT,
            self.update_output_event,
            self.input_textbox
        )

        return panel

    def create_output_panel(self):
        panel = wx.Panel(self)
        sizer = wx.BoxSizer(wx.VERTICAL)

        self.output_textbox = wx.TextCtrl(
            panel, -1, style=wx.TE_MULTILINE | wx.TE_READONLY
        )

        sizer.Add(wx.StaticText(panel, -1, 'Output:'), border=5,
                  flag=wx.ALL | wx.TOP | wx.LEFT | wx.RIGHT)
        sizer.Add(self.output_textbox, proportion=1, border=10,
                  flag=wx.EXPAND | wx.ALL)

        panel.SetSizerAndFit(sizer)
        return panel

    def update_output_event(self, event):
        self.update_output()

    def update_output(self):
        """Function that checks the values in all controls and updates the
        output."""
        r = self.regex_textbox.GetValue()
        text = self.input_textbox.GetValue()

        # Fetch the regex flags.
        flags = 0

        if self.flag_dotall_checkbox.GetValue():
            flags |= re.DOTALL
        if self.flag_ic_checkbox.GetValue():
            flags |= re.IGNORECASE
        if self.flag_ext_checkbox.GetValue():
            flags |= re.VERBOSE
        if self.flag_multiline_checkbox.GetValue():
            flags |= re.MULTILINE

        # Fetch the function choice.
        if self.func_search_radio.GetValue():
            fn = re.search
        elif self.func_match_radio.GetValue():
            fn = re.match
        elif self.func_findall_radio.GetValue():
            fn = re.findall
        else:
            wx.MessageBox('None of the functions are chosen... Somehow.')
            return

        # Try to perform the regex match. On error, display the error in the
        # status bar.
        try:
            result = fn(r, text, flags)
        except sre_constants.error as e:
            msg = 'Regex compilation error: ' + e.message
            self.SetStatusText(msg, 1)
            return

        # Empty the error part of the status bar just in case.
        self.SetStatusText('', 1)

        # If there is a result to the match or search function.
        if result and fn is not re.findall:
            output = dedent(u"""
                Match: {}

                Groups: {}

                Group dict: {}
            """)

            output = output.format(
                repr(result.group()),
                repr(result.groups()),
                repr(result.groupdict())
            )

        # If there is a findall result.
        elif result and fn is re.findall:
            output = u"Matches: " + repr(result)

        # No result.
        else:
            output = u"No matches."

        # Set the result text.
        self.output_textbox.SetValue(output)

    def on_close(self, event):
        self._mgr.UnInit()
        del self._mgr
        self.Destroy()

class RegexTesterApp(wx.App):
    def OnInit(self):
        mainframe = RegexTesterFrame()
        mainframe.Show()

        self.SetTopWindow(mainframe)
        return True

def main():
    app = RegexTesterApp(True)
    app.MainLoop()

if __name__ == '__main__':
    main()