We have the following problem:
How can I display a .png image?

GuiXT currently supports .bmp, .gif and .jpg, but not .png. You can use "GuiXT controls" component to display the .png image.

Option 1:
Control (10,1) (16,80) name="my_image" progid="c:\temp\img100.png"

Option 2:
Control (31,1) (47,80)  name="ie" progid="Shell.Explorer"

CallVBS display_picture "&V[ie]" "c:\temp\img100.png"

with the following VBScript function: 

Const READYSTATE_LOADING=1

Function display_picture(ie,path)

  ' open a blank HTML page

  ie.Navigate("about:blank")

  ' wait until Internet Explorer control document has been fully loaded 

  Do

   guixt.DoEvents()

  Loop While ie.ReadyState=READYSTATE_LOADING

  ' Suppress scrollbars

  ie.document.body.style.overflow = "auto"

  ' no margin

  ie.document.body.style.margin = "0px"

  ' use <img> tag with the given path

  ie.document.body.innerHTML = "<img width=100% height=100% src='" + path + "'>"

End Function

With Option 2 you have more freedom to define the layout using well documented HTML features such as style attributes. See for example:

http://msdn.microsoft.com/en-us/library/ms537842(v=vs.85).aspx