Background image in a panel for a newbie

Hello,

I have a frame and I display a background image in it,
using the code below. This works fine. Now, as I
would like to add buttons and other widgets, I'm adding
a panel to the frame (see the line commented out at the
bottom of the script) and my picture image.jpg gets
reduce to a small square on the upper left side of the
frame.

What am I missing.

Thanks.

Raphael

···

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# Background image class
class backgroundImage(wx.Window):
    def __init__(self, parent, image):
        wx.Window.__init__(self, parent)
        self.image = image
        self.Bind(wx.EVT_PAINT, self.OnBackgroundPaint)
        
    def OnBackgroundPaint(self, event):
        dc = wx.PaintDC(self.panel)
        dc.DrawBitmap(self.image, 0, 0, True)

# Main frame class
class myFrame(wx.Frame):
    def __init__(self):
        self.backImg = wx.Bitmap("image,jpg", type = wx.BITMAP_TYPE_JPEG)
        self.xSize = self.backImg.GetWidth()
        self.ySize = self.backImg.GetHeight()
        wx.Frame.__init__(self, None, -1, "EV", size=(self.xSize, self.ySize))
        win = backgroundImage(self, self.backImg)
# panel = wx.Panel(self, -1)

class MyApp(wx.App):
etc...