Python toolbox - check for nested group layers, and 2 more ?'s

Zeke

I have a python toolbox which crawls directories, or optionally a single mxd, and writes out various properties of the layers in them to a csv file, mostly interested in the data source. This works great, except...,.

1. I check for group layers to skip those. The tool does skip top level group layers, but not group layers nested in other group layers. How can I skip those?
2. I originally set a default location and file name for the output csv file, which the user can change. This works if the file doesn't already exist, but if it does, that parameter gets a big red X when the tool is run. The file is set to 'w', so I assumed it would just overwrite the existing file. Is it possible to do what I thought would happen?
3. In the self.description in the __init__ function, I'd like to break the text on different lines and paragraphs. But no matter how many \n's I add, the tool ignores them when run, and collapses the text into one block. Is there a way to accomplish this?

Thanks, relevant code below.

for mxd_path in mxd_list:
    try:
        mxd = arcpy.mapping.MapDocument(mxd_path)
        dflist = arcpy.mapping.ListDataFrames(mxd)

        for df in dflist:
            for lyr in arcpy.mapping.ListLayers(mxd, '', df):
                if not lyr.isGroupLayer:
                    nm = lyr.name
                    ds = '-- X --'
                    if lyr.supports('dataSource'):
                        ds = lyr.dataSource
                    lyr_attributes = [mxd_path, nm, ds]
                    writer.writerow(lyr_attributes)
                else:
                    if not lyr.isGroupLayer:
                        arcpy.AddMessage('\nLayer {0} does not support the dataSource property'.format(nm))
                        unsupported.append(nm)
                        lngnm = lyr.longName
    except Exception as e:
        arcpy.AddError('EXCEPTION: {0}\t{1}\t{2}'.format(mxd_path, lngnm, e))
        continue
    writer.writerow([''])
    del mxd

RebeccaStrauch__GISP

Greg, for what it's worth, check out my Python addin for data inventory and “broken-link” repair.

I've had to deal with a lot of the same issues you had with groups, etc.  To keep my files unique, I append the name with a datetime.  I also write out to a .csv and a report, with an option for a FGDB (but never found a reason for it for my broken-link list).

I had some other tools on this toolbar, but decided to simplify is for sharing.