Description
GeoSep is a plugin which puts a serpator in your GeoBars . Nothing about it can be modified, at all.
Author and Download
It was created by someone a long time ago, and it is distributed with the release versions of GeoShell.
If you want to use it, I suggest you don't. Instead look at GeoNSep - it does everything that GeoSep does, and more. (Although, GeoNSep has kind of a sucky name
)
On the other hand... since the release of Geoshell 4.10.x beta, GeoSep can be skinned, GeoNSep can't. So... it's up to you. 
Skinning GeoSep
To get skinnable seperators, you will have to be using GeoShell 4.10.x beta or newer. This plugin does not need configuration as is meant to use the current skin of the bars it is loaded on. Files for your images should be 30 pixels high for horizontal bars and 30 pixels wide for vertical bars (the other demensions are variable) and should be stored in the folder of the skin they are designed to be used with as bitmaps named 'sep.bmp' and 'vsep.bmp'.