[<fretfind@fr...>]

>> If an error requiers "Dont show this message again" then it cannot be
>> that important.
>
> No. It is important for first time launch, and the checkbox is a way
> to limit it to the first time only.

Perhaps, check the checkbox by default so that it is limited to the first
time.

Softening the wording of the message might be a good idea.
"Welcome to Inkcape. Inkscape's functionality can be extended by
installing and configuring various other applications and scripts. Some o=
f
these extensions are not installed. Please see /path/to/extension.log for
installation instructions."

Maybe a "view extension log" button on this dialog and in the preferences
too?

Aaron Spike