blitz3d bug

No, your png isn't ok.

  TabPage_Height = XGui_ImageHeight2("test.png")

  Print TabPage_Height
  WaitKey()

  Function XGui_ImageHeight2(path$)
   img = LoadImage(path$)
   If img = 0 Then RuntimeError "Image " + path$ + " not found."
   h = ImageHeight(img)
   FreeImage img
   Return h
  End Function

Test this, it works with every Image.