Comment 2 for bug 642522

There is a hidden preference on can set, apparently intended to show the 'extension-error.log' file at startup, but it doesn't work for me with Inkscape 047 and 0.48 on Mac OS X 10.5.8:

    <group
       id="extension-error"
       show-on-startup="1" />

The log file from loading extensions [1], while useful for tracking down problems with missing supported file formats, at the same time seems to be confusing for normal users (as far as I can tell from discussions on InkscapeForum.com), because it lists all extensions that fail to load due to missing a known dependency: some of the file formats or extensions many Windows users rarely use (LaTeX, XFIG, DIA or SKETCH files), and some of the extensions are not yet cross-platform (Save as XCF, import Text file, ...).

Attached is the log file from vanilla Inkscape 0.48 on Mac OS X (note that extensions that need UniConvertor are not listed but fail to execute nevertheless because UniConvertor is not tested as explicit dependency, yet it is not installed or bundled with Inkscape on OS X).

Maybe this feature request could be expanded into a more general one for better notifying the user of missing dependencies at run-time, across platforms, for all script-based extensions:
- inform users why an extension fails to load
  (file format not listed in the 'Open/Save' dialog)
- inform users why an extension fails to run
  (error message when opening/saving a file or executing an extension)

[1] linux/osx:
~/.config/inkscape/extension-errors.log
    Windows:
%APPDADA%\Inkscape\extension-errors.log

    XP:
C:\Documents and Settings\[USERNAME]\Application Data\Inkscape\extension-errors.log
    Windows Vista / 7:
C:\Users\[USERNAME]\AppData\Roaming\Inkscape\extension-errors.log