Actually, this is about more than just deleting brushes, it is also about the file dialog, and how it works under Windows. I am using Gimp 2.6.10 in Windows-7. I have been using Gimp for several years, but never a heavy user, just occasional when I have to take a few pounds off the wife, or otherwise repair a family photo, or just feel like dabbling.
I had several times wanted to add a little "Look here" arrow to images to help with explaining or asking a question, and last night I decided to add a brush in the shape of an arrow to allow quickly inserting such an arrow. I had never added a custom brush, so I looked in the Gimp "help" and found it pretty quickly. Then, I got careless. I did not read carefully, and I must have had too much wine. I knew better anyway, but, I saved my new brush in the System brushes folder rather than my personal brushes.
Well, the new brush was not quite what I wanted, so I decided to start over, but now this brush (like all system brushes) is read-only, will not delete, will not edit. No problem, I thought, I will just go delete the file for this brush manually. Windows Explorer opens and I navigate to
"C:/Program Files/GIMP-2.0/share/gimp/2.0/brushes/"
There are a bunch of brush files, But there is no file named upArrow.gbr
In Gimp, from the brush menu, I copy the brush location, I get
file:///C:/Program%20Files/GIMP-2.0/share/gimp/2.0/brushes/UpArrow.gbr
Again in Gimp, I trace my steps for saving the brush, back to the system brushes folder, and there is a file already there, upArrow.gbr... but not in Windows Explorer...
I could learn to live with the extra not-quite-right brush stuck on the brushes tool box, but I will never sleep comfortably until I know why the Gimp "File-Save-as" file manager shows a file that the Windows file manager (and command line DIR and ATTRIB) does not show.