>  I've included a short code example exhibiting this 'illegal icon
specified' error.
>  What I'm trying to do here is pretty simple. I have a FXTreeList that I
want to
> wipe clean and populate with new FXTreeListItems. It works fine until the
new
> tree list item has an icon (closed or open state) different from the icon
that was
> displayed for the original tree list item. Then I get the error I wrote in
the
> subject of this note.

This question is covered in the FAQ:

    http://www.fox-toolkit.org/faq.html#ILLEGALICON

For this case, I would just modify your TreeChecker#create method to look
like this:

    def create
        super
        @icon1.create
        @icon2.create
        show(PLACEMENT_SCREEN)
    end

>  Does anyone see what I'm doing wrong here? I'm running Andy's 1.6.5
Windows
> distribution and FXRuby 0.99.188 supplied by Lyle. I am willing to upgrade
if
> that will solve this problem.

You do not need to upgrade to fix this particular problem, although
generally speaking I'd recommend an upgrade since 0.99.188 is a pretty old
version at this point. Other bug fixes and improvements have been made since
that version.

Hope this helps,

Lyle