Sakura is a Knowledge Navigator and User Interface for UNIX, which implements HyperMedia and its own windowing and packing system, both in the main program and in an extensive API for Tcl and other languages.
Highly customizable program that manages contents
of several clipboard (like X11 buffers) pockets.
User can define (in a HLL) actions to be done when
something is performed with the clipboard
(pasting, selecting, hovering, etc.)