Xfce4-clipman-plugin is a plugin for the Xfce Panel and as a standalone application (it is a bundle). It keeps the clipboard contents around (even after an application quits). It is able to handle text and images, and has a feature to execute actions on specific text selection by matching them against regexes.
Xfce4-clipman-plugin documentation
See NEWS for details on changes and fixes made in the current release.
For concrete information on the minimum required versions, check configure.ac.in.
Xfce4-clipman-plugin source code
Xfce4-clipman-plugin archive or Xfce4-clipman-plugin tags
From source code repository:
% cd xfce4-clipman-plugin
% ./autogen.sh
% make
% make install
From release tarball:
% tar xf xfce4-clipman-plugin-<version>.tar.bz2
% cd xfce4-clipman-plugin-<version>
% ./configure
% make
% make install
Visit the reporting bugs page to view currently open bug reports and instructions on reporting new bugs or submitting bugfixes.