9/Sep/2002: Viewing of Before/After optimisation progress implemented.
CompResults panels now retain a memory of the last-used-tab. Viewing of
eigenvalues (aka orbital energy levels) is now implemented, and quite
pleasant to use.

13/Sep/2002: Editing group properties in 3D structures now possible - spin
and charge can be set for groups. These are heeded by Xentark during
calculations. Also, DiagramStructure's atom drawing is improved.

14/Sep/2002: More synchronisation between the 2D and 3D structure
codebases. Now cutting and pasting is interchangeable between 2D and 3D
structures. 2D and 3D now both use math rather than screen coordinates,
i.e. Y axis is up rather than down. The "Trash All Results" button in
CompResults has been made somewhat more elegant.

15/Sep/2002: Lots more miscellaneous bug fixes and barely noticeable user
interface improvements, but most of all, Print and Output to Metafile are
now functional, and implementations are available in the 2D and 3D panels.

26/Sep/2002: A new panel has been implemented for CompResults properties:
Progress Graph, which charts a quick summary of computational optimisation
parameters as they go. It looks nice. A less obvious improvement has been
made to the local pseudoserver (i.e. direct file access): now multiple
instances of Xykron and Xentark can access the same files without such
serious problems of conflicting/overwriting data. As long as both instances
are not trying to modify an object at the exact same time, multiple
sessions will not erase each other's data.

28/Sep/2002: Communication logging has been added, using a command line
flag. Minor interface bug fixes, and an important Undo/Redo bug fixed. New
interface and communication functionality which allows whole Objects or
Collections to be copied to the clipboard, and paste back.

29/Sep/2002: Object templates have been implemented, i.e. new objects can
by conveniently selecting a from one of any number of designated template
objects. Also, in the DiagramStructure panels, vertical/horizontal bonds
are "nudged into alignment".

3/Oct/2002: The concept of "Constraints" has been introduced, initially
just for UserText, but is about to become an integral part of Text, Scalar
and KeyValue properties.

4/Oct/2002: Some of the CompResults panels are now printable, in
particular the orbital energy levels and the enhanced structure views.

5/Oct/2002: Adding hydrogens in the 3D structure editor is now more
sensibly handled: the algorithm looks for the "emptiest" immediate region
of space and places the hydrogen there, followed by several quick OptiClean
cycles. A new kind of panel has been added, when the user highlights
objects or collections: a text list of the contents presents itself on the
main panel, instead of just blank nothingness. The first simple Scalar type
has been implemented (Number), with associated constraints.

6/Oct/2002: PhysicalProperty types have been implemented, with most of the
associated constraints logic.

7/Oct/2002: The special CollectionPanel now summarises the contents of the
properties contained within, rather than just enumerating them.

12/Oct/2002: Literature and ElementalAnalysis types are now implemented.

13/Oct/2002: UserKeyValues are now implemented.

19/Oct/2002: The UserText property has been extended to permit values to be
restricted to/selected from a list.

24/Oct/2002: The OptiClean (molecular mechanics) feature has been
rewritten, and is much better, although not quite finished.

26/Oct/2002: Iterative improvements. OptiClean is closer to complete, 
eigenvalues display and print better, moving a single atom in the 3D
editor is less annoying, adding hydrogens works properly, renaming and
creating entities in the local realm is now proof against accidental
duplication, and a few other tweaks.

27/Oct/2002: Formula properties can now be "linked" to Diagram or Model
structures, enabling them to be computed automatically. Also, the help
files are a bit closer to being complete.

14/Nov/2002: An "autobond" feature has been implemented, just in case a
structure with atomic coordinates but not bonds is available.

16/Nov/2002: Now when Xykron loads up for the first time, and creates its
directory in the user's home, it will attempt to make symbolic links to
the <CODE>templates/</CODE> and <CODE>demo/</CODE> directories if they
have been installed in the common location. This is a particularly
convenient feature for RPM installations.<BR>&nbsp;&nbsp; A new output
feature has been added, which allows the printable panel types to be made
into a bitmap (PNG), of user-selected dimensions and a colour of choice.
This is a more powerful alternative to taking screenshots.
<BR>&nbsp;&nbsp; A new tab has been added to the Setup dialog, which
currently allows some printing/output features to be setup as defaults
(things like paper size, output filename, etc).

22/Nov/2002: Minor fixes (can now delete non-empty local Objects, and the
Progress Graph does not anymore chew up bandwidth until it gets selected).

23/Nov/2002: Minor fix (previously the default Realm(s) would not be
realised until the 2nd time Xykron was run).

24/Nov/2002:  The first benefit is that SVG (Scaleable Vector Graphics) is
used instead of the proprietary Qt Metafile format, which means they could
actually be useful for something.  Click <A
HREF="preview_newmeta.svg">here</A> to try it out. Unfortunately SVG
support in mainstream applications seems to be pretty miserable at
present, but by all accounts it is the next big thing in cross-platform
vector graphics - I can't even find a viewer for Linux that isn't broken
or pre-pre-alpha, but fingers crossed for SVG support in Mozilla (?).

21/Dec/2002: Xykron now has an important new feature: Structure templates,
which work quite similarly for both the DiagramStructure and
ModelStructure editors.  The templates are structure fragments, which are
entirely configurable, being dynamically compiled from several Objects in
the local /templates/ Container. Templates are typically fragments such as
rings, functional groups, structural subunits, etc - but there are no
restrictions on what can be defined. <IMG SRC="preview_templates.png"
ALIGN=right><BR CLEAR=ALL>

4/Jan/2003: A bunch of minor improvements of the bugfix/improved user
interface variety. Cutting and pasting structures is improved, and placing
2D structures into a 3D panel recreates stereochemistry and implied
hydrogens. A new feature: Insert Template extends the utility of Object
templates (local:/templates), allowing them not only to form the basis of
newly created objects, but also to allow one to be inserted as a Collection
inside an already existing Object. Also, a feature in the Right-click tree
menu called "Clone" makes it easier to duplicate existing entities.

5/Jan/2003: A new feature has been added to ModelStructure: flatten rotate,
which spins the structure around to fit it flat on the page as best
possible.

11/Jan/2003: Behaviour of a couple of panels with regard to hogging 
network resources until finished has been fixed. ModelStructure panels now
allow rotation of just the selected atoms, either about the origin or about
their centre of gravity. Several bugfixes.

12/Jan/2003: Xykron now has somewhat improved export/import capability.
Options from the main menu allow any type of Property to be exported to an
XML file, and for structures to be exported to MOL-files. Existing XML and
MOL-files can be imported into new Properties. Some bugs in MOL-file
reading/writing were fixed.

17/Jan/2003: Interface improvements to 2D & 3D panels. Additionally, the
functionality of these panels has undergone a major internal code overhaul
to abstract common functionality. Expect more consistency between the two
interfaces in the future - and possibly a temporary glitch or two. Other
minor bug fixes.

22/Jan/2003: Simple feature added to export structures in a very simple
comma-delimited text format, simple to convert to input for external
computational programs.

23/Jan/2003: Internal difference to the way implicit hydrogens are handled
for 2D: they are now stored in a special field, which is recalculated
regularly by the display widget. Having the data stashed away means that it
is available even if the algorithm for recalculating it is not. A glitch
was fixed in the "snap to" code for drawing 2D structures.

25/Jan/2003: Five more 3D structure glitches fixed. OptiClean now has the
sense to know when to stop, rather than just going on forever.

2/Feb/2003: Importing JCAMP-DX spectra has been implemented; a subset,
anyway. The various dialects seem to be a veritable Tower of Babel, so
only the simple ones work. IR and Mass spectral data has the best chance
of working. Also, modification of some of the CompResults datastructures,
to incorporate anticipated calculated properties from external sources.

7/Feb/2003: The CompResults panel can now show orbital populations other
than whole numbers, if they are available - although Xentark cannot
calculate them, the data can be imported from elsewhere (more on this
later). A minor bugfix with regard to inserting templates into objects or
collections.

9/Feb/2003: New functionality has been introduced to add and maintain
scheduled computation tasks (Xuru). This functionality is only available
with remote (Xortoth) Realms. Minor addition to structure storage: atomic
number is now stored as part of the XML, to assist interaction with other
software.

23/Feb/2003: Rotation of selected points (about the Z-axis) has been
implemented for 2D structure diagrams. 3D structures now have a "centre"
menu option, which translates the structure to its centre of gravity.

8/Mar/2003: Important new feature added to Xykron: symmetry.
ModelStructures can now have up to 7 symmetry elements defined: inversion,
mirror plane (XY,XZ,YZ) and rotation (X,Y,Z; up to 8 orders). These
symmetry elements are honoured (i.e. enforced) during editing and rotating
of structures. OptiClean also observes symmetry rules. The
Sch&ouml;enflies point group symbol is calculated automatically, and will
be passed to computational programs, including Xentark. Note: at present
Xentark's underlying MPQC library is a bit finicky about symmetry - this
will be addressed.

9/Mar/2003: General improvements to OptiClean (effective use of symmetry,
fixed a problem with flat trigonal centres, and improved aesthetics when
rotating bonds). More convenience access to "special" menu options in
ModelStructure editing, and a set of features for rotating through 90&deg;
increments, which conserves any defined symmetry operations. Also, keyboard
accelerators for the 2D/3D panels work properly now (some Qt-weirdness has
been worked around).

21/Mar/2003: A new series of display modes have been implemented for
viewing molecular orbitals ("spatial data"), which resemble space-filling
representations generated by OpenGL or ray-traced images, but do not
require any such fanciness. The drawing is not exactly snappy, so when the
structure is rotated, the regular wireframe drawing method is used. The
three new styles are: Solid, which is fairly conventional; Merged, which is
not quite distinct just yet, and Translucent, which looks a bit sci-fi.

30/Mar/2003: Eigenvalue (orbital energy level) viewing now shows
transition probabilities, when available. Also, the CompResults panel has a
viewer for electronic excitations, which it presents as a simulated UV-Vis
spectrum.

12/Apr/2003: A minor glitch fixed which prevents overly-long summary
enumerations of collections from blocking the user interface.

26/May/2003: An additional "when to stop" clause added to the OptiClean
algorithm, which should improve results in many cases. Graphical glyphs
are now used to denote particular symmetry elements in 3D structure
display.

17/Aug/2003: Display of predicted electronic spectra now offers additional
levels of control (wavelength range and whether to include only ground
state excitations).
