An Autodesk Softiamge plug-in that shows how to use wxPython from inside a command.

WxSceneInfoPlugin.py

# By Mohammad "ShaderOp" Abdulfatah
#
# This little sample demonstrates how to use wxPython to display
# a dialog box inside Autodesk Softimage. It attached an item
# to the "Window" menu named "WxSceneInfo", which executes a
# a command that shows a wxPython dialog box with a labed and
# two buttons. One button adpats the label with the number
# of top-level objects in the current scne, and the other creates
# a polygonal cube.
#
# Modifying this code to work wiht PyQT should be trivial.
#
# For questions, comments, and feedback, you can reach me
# through my website at http://shaderop.com/contact/

import win32com.client
from win32com.client import constants
import threading

# This will be used to ensure that only one copy of the dialog
# is running.
is_dialog_running_event = threading.Event()

def XSILoadPlugin(in_reg):
  in_reg.Author = "Mohammad Abdulfatah"
  in_reg.Name = "WxSceneInfoPlugin"
  in_reg.Major = 1
  in_reg.Minor = 0

  in_reg.RegisterCommand("WxSceneInfo","WxSceneInfo")
  in_reg.RegisterMenu(constants.siMenuMainWindowID,
    "WxSceneInfo_Menu",
    False,
    False)
   
  #RegistrationInsertionPoint - do not remove this line

  return True

def XSIUnloadPlugin(in_reg):
  strPluginName = in_reg.Name
  return True

def WxSceneInfo_Init(in_ctxt):
  oCmd = in_ctxt.Source
  oCmd.Description = "Wx Scene Info"
  oCmd.ReturnValue = True

  return True

def WxSceneInfo_Execute():
  # only launch the dialog if it's not already running.
  if is_dialog_running_event.is_set() == False:
    __queueCommand(runDialog)
  else:
    # It's probably a good idea to somehow notify the user that
    # the dialog is already running.
    pass

  return True

def WxSceneInfo_Menu_Init( in_ctxt ):
  oMenu = in_ctxt.Source
  oMenu.AddCommandItem("WxSceneInfo","WxSceneInfo")
  return True

def runDialog():
  # Any attempt to import the wx module on the main application thread
  # will cause Softiamge to crash and burn, but since this method runs
  # on a separate thread and has its own message loop, importing wx
  # will work here.
  import wx	

  # Now go to town
  class MyFrame(wx.Frame):
    def __init__(self, title):
      wx.Frame.__init__(self,
        None,
        size=(400,300),
        style=wx.DEFAULT_FRAME_STYLE,
        title=title)
                        
      # set background color to SI's signature desert gray.
      self.SetBackgroundColour(wx.Color(171, 168, 166))
      self.Bind(wx.EVT_CLOSE, self.OnClose)
    
      self.objectCountLabel = wx.StaticText(self,
        label="Number of objects in scene:",
        pos = (10, 10),
        size = (300, -1))
      self.refreshButton = wx.Button(self, label = "Refresh", pos = (310, 10))
      self.Bind(wx.EVT_BUTTON, self.OnRefresh, self.refreshButton)
      
      self.createCubeButton = wx.Button(self,
                                      label="Create cube",
                                      pos=(310, 50))
      self.Bind(wx.EVT_BUTTON, self.OnCreateCube, self.createCubeButton)

    def OnRefresh(self, event):
      count = Application.ActiveSceneRoot.Children.Count
      label = "Number of objects in scene: {0}".format(count)
      self.objectCountLabel.SetLabel(label)

    def OnCreateCube(self, event):
      Application.ActiveSceneRoot.AddGeometry('Cube', 'MeshSurface')

    def OnClose(self, event):				
      self.Destroy()
      # IMPORTANT: Must release the event once the windows is closed,
      # else the dialog won't launch again until after SI is restarted
      global is_dialog_running_event
      is_dialog_running_event.clear()

  app = __getApplication()
  frame = MyFrame("Hello World")
  frame.Show(True)
  is_dialog_running_event.set()
  app.MainLoop()


# Following code is copied almost verbatim from Houdini 9.5 sample
# code at http://www.sidefx.com/docs/houdini9.5/hom/cookbook/pyqt/

__command_queue = []
__command_queue_lock = threading.RLock()
__command_queue_event = threading.Event()

__wx_thread = None

def __queueCommand(callable, arguments=()):
  global __wx_thread

  if __wx_thread is None:
    __wx_thread = threading.Thread(target=__wxThreadMain, name="wxThread")
    __wx_thread.start()

  __command_queue_lock.acquire()
  __command_queue.append((callable, arguments))
  __command_queue_lock.release()

  __command_queue_event.set()

def __wxThreadMain():
  while True:
    __command_queue_event.wait()
    __command_queue_lock.acquire()
    command = __command_queue.pop()
    __command_queue_event.clear()
    __command_queue_lock.release()

    command[0].__call__(*command[1])

__wx_app = None

def __getApplication():
  import wx
  global __wx_app
  if __wx_app is None:
    __wx_app = wx.App(False)
  return __wx_app