To install: 
Copy all files into ~/.gnome2/gedit/plugins
Open gedit, go to Edit->Preferences->Plugins
Enable the plugin named Project Manager

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Project Manager -- a plugin for gedit
Copyright (C) 2008 Jeff Shipley (2008)

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program.  If not, see <http://www.gnu.org/licenses/>.

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This plugin is still in an early stage of development, it opens a project
from a hard coded location, and displays the project file in a tree view
in gedit's sidebar