Display transparent image as overlay

I am trying to create a program that simply displays a PNG (that has transparency), the image will be a map protractor that can be dragged around on the screen while viewing land navigation maps. I found the following example which almost does what I’m after, except SetTransparent() changes the alpha of the image too which i do not want, and it would be nice to get rid of the borders around the window as well (show image only).

import wx

class Frame(wx.Frame):

    def __init__(self, image, parent=None, id=-1,pos=wx.DefaultPosition, title='wxPython'):
        temp = image.ConvertToBitmap()
        size = temp.GetWidth(), temp.GetHeight()
        wx.Frame.__init__(self, parent, id, title, pos, size)
        self.bmp = wx.StaticBitmap(parent=self, bitmap=temp)

class App(wx.App):
    def OnInit(self):
        image = wx.Image('1.png', wx.BITMAP_TYPE_ANY)
        self.frame = Frame(image)
        return True

app = App()