wxPython example. A jigsaw puzzle (3). MS Windows a double buffer

This is a continuation of the previous two entries. I finally got the chance of testing the puzzle on windows and it didn't show properly it flicked a lot. Then I learn that the Windows platform doesn't implement a double buffer so I have to do it.
The idea is painting to a bitmap and then copy it to the DC on the OnPaint event. This solution improved a lot the way application was shown it didn't removed he flicks completely.
After some research I found the solution by capturing the EVT_ERASE_BACKGROUND event and do nothing with it. This fixed all the issues. It also important to call the Update method after the Refresh.

The new board.py code is:

#!/usr/bin/python  

import wx
import stateDB
import rectangle

class Board(wx.Panel):
    boardId = 77
    def __init__ (self, parent, pieces, count, seconds, allowRotation=True):
        wx.Panel.__init__(self, parent, style = wx.NO_FULL_REPAINT_ON_RESIZE)

        self.db = stateDB.StateDB()

            
        self.pieces = pieces
        self.dragged = None
        self.count = count
        self.completed = False

        self.seconds = seconds
        self.timer = wx.Timer (self, wx.ID_ANY) 
        self.Bind (wx.EVT_TIMER, self.OnTimer, self.timer)
        self.timer.Start (1000, False)
        self.printStatus ()

        self.Bind (wx.EVT_PAINT, self.OnPaint)
        self.Bind (wx.EVT_ERASE_BACKGROUND, self.OnEraseBackground)
        self.Bind (wx.EVT_SIZE, self.OnSize)
        self.Bind (wx.EVT_LEFT_DOWN, self.OnDown)
        self.Bind (wx.EVT_LEFT_UP, self.OnUp)
        self.Bind (wx.EVT_MOTION, self.OnMouseMotion)
        if allowRotation:
            self.Bind (wx.EVT_RIGHT_UP, self.OnRight)

    def SaveStatus(self):
        self.db.initiateDB ()
        self.db.saveEverything (Board.boardId, self.count, self.seconds, \
                self.pieces)

    def printStatus (self):
        mins = self.seconds%(60*60)/60
        minStr = str(mins)
        if (mins < 10):
            minStr = '0' + minStr
        secs = self.seconds%60
        secStr = str(secs)
        if (secs < 10):
            secStr = '0' + secStr
        timeStr = str(self.seconds/(60*60)) + ':' + minStr + ':' + secStr

        if self.completed: 
            status = 'Completed: ' + timeStr
        else:
            status = str(self.count) + ': ' + timeStr
        self.GetParent().statusbar.SetStatusText (status)

    def OnTimer (self, e):
        if not self.completed:
            self.seconds += 1
            self.printStatus ()

    def OnEraseBackground (self, e):
 """ To avoid flickering in windows"""
        pass

    def OnPaint (self, e):
        dc = wx.BufferedPaintDC(self, self._Buffer, wx.BUFFER_VIRTUAL_AREA)

    def draw (self, dc):
        dc.Clear ()
        for p in self.pieces:
            p.drawPiece (dc)

    def UpdateDrawing (self):
        dc = wx.MemoryDC ()
        dc.SelectObject (self._Buffer)
        self.draw (dc)
        del dc
        self.Refresh ()
        self.Update ()

    def OnSize (self, e):
        s = self.ClientSize 
        self._Buffer = wx.EmptyBitmap (*s)
        self.UpdateDrawing ()
 

    def OnDown (self, e):
        mousePos = e.GetPosition()

        # The iteration is reversed so the piece on top is choosen 
        indexes = range(len(self.pieces))
        indexes.reverse()
        for i in indexes:
            if self.pieces[i].checkPointInPiece (mousePos):
                # Put the selected at the end of the list so it's painted the last
                p = self.pieces[i] 
                self.pieces.append(p)
                del self.pieces[i]
                self.dragged = len(self.pieces) -1
                break

    def OnUp (self, e):
        if self.dragged != None:
            mousePos = e.GetPosition()
            for i in range(len(self.pieces)):
                if (self.dragged != i):
                    if self.pieces[self.dragged].checkPieceMatch (\
                            self.pieces[i]):
                        del self.pieces[i]
                        #self.Refresh()
                        self.UpdateDrawing ()
                        self.count += 1
                        self.printStatus ()
                        self.SaveStatus ()
                        if len(self.pieces) == 1:
                           if (self.pieces[0].getOrientation() ==\
                                   rectangle.Orientation.or0):
                               self.db.RemoveDBFile ()
                               self.completed = True
                               self.printStatus ()

                        break
            self.dragged = None

    def OnMouseMotion (self, e):
        if self.dragged != None:
            mousePos = e.GetPosition()
            self.pieces[self.dragged].movePiece (mousePos)
            #self.Refresh()
            self.UpdateDrawing ()

    def OnRight (self, e):
        mousePos = e.GetPosition()
        indexes = range(len(self.pieces))
        indexes.reverse()
        for i in indexes:
            if self.pieces[i].checkPointInPiece (mousePos):
                self.pieces[i].incrementOrientation()
                newPos = self.pieces[i].calculateCenterPosition()
                self.pieces[i].changeRelPosition (newPos)
                self.pieces[i].checkPointInPiece (mousePos)
                #self.Refresh()
                self.UpdateDrawing ()
                if len(self.pieces) == 1:
                   if (self.pieces[0].getOrientation() == \
                           rectangle.Orientation.or0):
                       self.completed = True
                       self.printStatus ()
                break

class Puzzle (wx.Frame):
    def __init__ (self, parent, id, title, pieces, boardSize, count,
            seconds, allowRotation=True):
        wx.Frame.__init__(self, parent, id, title, size=boardSize)

        self.statusbar = self.CreateStatusBar()
        self.board = Board(self, pieces, count, seconds, allowRotation)

        self.Centre()
        self.Show(True)