since development moved to GitHub, the list of changes here may not be up to date.
The most accurate list of changes will be GitHub commit history:
https://github.com/aardappel/treesheets/commits/master

2013-06-02:
- TreeSheets is now open source! https://github.com/aardappel/treesheets
- you can now set the background color on a per document basis
- you can now turn off cursor key navigation of in between cell locations
- integrated new wxWidgets 2.9.4, which probably fixed a lot of problems, particularly on OS X (which has now graduated from Alpha to Beta :).
- you can now pick a default font size when you pick a default font. This is a per user setting, not per document, other users will open your documents at their preferred size.
- Edit -> Copy As Continuous Text puts a single line of text merged from any selection into the clipboard. Useful for merging the text of multiple small cells, 
  or making a paragraph out of many cells for use in another application.
- home/end now move within a line, whereas ctrl+home/end move within the entire text of the cell
- improved rendering of line rendering style and background color picking
- added additional space to cell margins
- hover over wasn't updated during mousewheel scroll
- optimized drag & drop of external files to not scroll/select while dragging
- fixed ALT+F etc. not popping up the File menu
- improved editing of search/replace boxes supporting shift+cursor/home/end etc.
- on Linux, the Fold operation is now SHIFT+F10 instead of F10 to not clash with Ubuntu pre-defined keys.

2012-04-07:
- fixed bug caused by right-clicking on a modified selection
- possibly fixed problem related to "automatically reload files" popping up multiple dialogs at once

2011-08-25:
- fixed missing UTF-8 charset header in HTML export
- fixed fold not being preserved on copy/past and undo
- Now detects when a file that is loaded has been modified on disk by another program / computer,
  and reloads the file automatically (if it hasn't been changed) or asks (if it has).
  This allows multiple computers to seamlessly work with 1 treesheets file over services like DropBox.
  This functionality is by default turned OFF (see Options -> Auto reload documents) because it is
  potentially expensive if the treesheets file is in a folder with lots of subfolders. 
  Also not working on network drives at the moment.
- HOME & END now change selection in a grid
- INS on a cell that already has a grid now selects the last line of that grid, ready for inserting an item
- fixed INS not unfolding a folded cell
- fix for broken OSX clipboard functionality
- added menu keyboard navigation accellerators
- fixed bug in CTRL+x on empty text selection
- fixed bug in CTRL+up/down in text edit mode

2011-04-30:
- fixed bug in horizontal cell layout text selection
- clear status message when switching tabs or entering search
- fixed bug in shift+cursor selection
- fixed semi-colon CSV import
- fixed loading a tmp file not marking the document as modified

2011-04-19:
- folding of grids: Edit -> Toggle Fold (F10) on cell(s) hides the grids they contain.
  Folded cells will be marked with a '+' symbol in front of them
  If you zoom into them, you will see the full grid, without having to fold/unfold.
  A nice alternative to shrinking text if your sheet gets too big.
- Redo (CTRL+y) now works.
- an image drop down menu provides a convenient set of images you can quickly add to selected cells
- there's now a strikethrough style (useful for todo/task lists!) using the CTRL+t shortcut (previously transpose)
- added alternative (black & white) toolbar icon set (see options menu)
- "Sort" now sorts on subsequent columns if data in the current column is equal
- "Sort" can now be either ascending or descending
- outputs statistics on file when loading
- added commands to reset text sizes, styles, colors and column widths within the current selection (see Edit menu)
- [making a lot of edits to a single cell will now set multiple undo points rather than just a single one] -> removed in favor of Redo
- added shift+del, shift+insert and ctrl+insert as alternatives for ctrl+x, ctrl+v, ctrl+c
- double clicking grid boundaries now selects that entire grid, not the parent cell
- option: render document centered or not
- option: minimize on close
- option: single click maximize from tray
- images in front of text rendered centered
- improved toolbar dropdown rendering & size
- images don't resize anymore when changing the text size of a cell,
  instead there's now a function to change the size of an image (Edit -> Images -> Scale)
- cells shrunks to tiny size don't show images
- documents always show a small gutter, regardless of size
- CTRL+f now selects any previous text in the search box, CTRL+a selects all, and HOME/END work too
- made the interactive tutorial the default help (F1), both it and the old html tutorial available from the menu
- selects the parent if you cut or delete all children & doesn't allow deleting of all children of the root of the current view
- fixed filtering making everything tiny if cell text of grid was filtered, now doesn't minimize cells with grids, just greys them out
- fixed text selection not showing correctly with image in front
- fixed failing autosave popping up endless dialog boxes
- fixed undo causing file to be marked as not modified
- fixed horizontal layout being reset by some operations
- fixed line style rendering sometimes having wrong background color
- fixed style settings on "Wrap in new parent"
- fixed statusbar items not showing fully on some systems
- fixed bug with badly formatted indented text not being pasted/imported properly
- fixed selection being off in scaled presentation mode
- fixed bug with international characters in filenames

2010-11-14:
- fixed selection box being rendered in the wrong location after switching resolutions
- fixed it repeatedly trying to save temp files when temp file saving fails

2010-10-15:
- fixed crash in "Hierarchy Swap" operation on leaf cells
- "escape" did not exit edit mode, as it used to
- new cells sometimes would not get applied the correct rendering style (from siblings or parent)
- changing fonts could leave other open documents with incorrect rendering
- transpose now keeps a selection

2010-10-10:
- fixed bug where text background would not be set correctly, mostly resulting in incorrect printouts

2010-09-28:
- fixed bug that would stop certain operations work on single cell grids (such as browse)

2010-09-20:
- Added new rendering options for grids, see tutorial.cts for examples, or todo_calendar.cts
- on multi line text, cursor up & down now moves line by line before moving to the next cell
- new tabs that have individual close buttons, can be reordered, and by default are at the bottom (use option to move them to the top)
  CTRL+TAB cycles thru all tabs
- CTRL+mouse drag moves a cell to a destination (like Cut + Paste)
  ALT+mouse drag copies a cell to a destination (like Copy + Paste)
- minimum size of sizing cells is now relative to the current view rather than the root of the document, allowing you to make extremely
  hierarchical documents (important for presentations).
- Some operations that work on grids and required you to select the parent cell to operate now also work if you simply select all cells of the grid.
  This is more intuitive to some people, and also allows these actions on the root grid, which didn't work before.
  Affected operations sofar: transpose, flatten, hierarchify, and the cell rendering options
- when loading a file that is already open, instead of the "this file is already loaded" dialog it now simply switches to the open document
- Added option to swap mousewheel scrolling and zooming operations (make scrolling require CTRL instead of zooming)
- Made top toolbar more compact to fit on netbook screens better
- Ctrl+W (close) or closing last tab now simply quits TreeSheets. CTRL+q quits / closes all tabs.
- When clearing a cell with delete/backspace, it now keeps its colors/styling
- Statusbar now shows date of last edit of cell you hover over. The furthest these dates go back is cells edited since the 2010-03-10 release
  of TreeSheets, since older versions didn't record this information.
- Fixed pasting of NxN grid selections into grids, it behaves much more logical now
- Fixed potential crash bug in closing tabs
- On paste, cursor is at the end of the pasted string
- New grids take default column width from their parent
- Added column sizing method that does not size any sub grids
- Improved line-splitting for ( and )
- Added remove image operation
- Added seperators to the menus for clarity, and moved some lesser used editing operations into submenus.
  The roundness setting now shows its current value.
- Fixed rendering of editing in presentation view
- Status bar updates even if mouse pointer doesn't move
- Fixed refresh error in Hierarchy Swap operation, and one related to scrolling
- Fixed filename being reset on a cancelled Save As
- Single instance check file under linux is now hidden
- Rewrote some of the column width related code to make it more robust, fixed several bugs in it

2010-03-22:
- "Paste Style Only" pastes only the color/style/image from the copied cell into the destination cells, not the text
- dragging middle mouse button (mousewheel down) now pans
- Scrolling smoother on "continous" mousewheels
- Fixed undo resetting column width to default
- Fixed zoomed in views sometimes not rendering correct background color

2010-03-10:
- Grid borders can now be rendered with round corners. The "roundness" can be set in the options menu.
- Added "tags". Tags make cell texts that are used repeatedly easier to assign, recognize, and keep consistent. See menu edit/tags.
- Added "Toggle Grid Below/Next to Text" (F7) for yet more flexible layout possibilities
- Added "Hierarchify" and "Flatten" operations that simplify data portability between TreeSheets and spreadsheets
- Added export to "CSV" format.
- Added "Hierarchy Swap" (F8) operation (see tutorial)
- Added "Wrap in new parent" (F9) operation to easily create new hierarchy (works on any selection)
- Added "filters" (see View menu). A filter forces all cells not included to be shown as 1 pixel characters in lighter grey,
  so its easy to focus visually on whats important in really large TreeSheets files. Currently, there's filters for the search
  results, and for a % percent of last edited cells. This feature works because TreeSheets now records the last edit time for
  each cell. Since older TreeSheets files do not have this information, it may take a while of editing before this feature becomes useful.
- Completely reworked how columns are sized. Now every column in a grid simply has a character width which can be resized by
  SHIFT+mousewheel as before, instead of the clumsy per cell linecount. Column width is shown in the statusbar.
  Resizing affects the column(s) spanning the current selection, and any grids inside of it. Layout is quicker and more
  predictable. Default column width is 80 characters, so you may have to resize some old treesheets files.
- When zooming in, now shows you the "context" of what you're looking at in light grey text (the text of all the parent cells)
- Added "Open File" (F4), which loads a filename in the associated application (paths relative to where the .cts is stored).
- Improved the UI to be more like other applications and more consistent. Primarily, the mousewheel and PgUp/PgDn now
  always work the same, without modifiers they scroll, with CTRL they zoom, with SHIFT they change text size, and with
  ALT they change column size.
- Support for mousewheel scrolling horizontally (on mice that support it) has been added (NOT TESTED).
- fixed bug where "replace" could loop indefinitely if the replacement string contained an occurrence of the search string :)
- Tabs are shown on the left by default (change in options)
- small improvements to the builtin programming language
- Option for faster line rendering (useful if you have very complex sheets, or lots of 1 pixel text)
- text rendering is lots faster on windows now
- Fixed bug in CVS import where it wouldn't parse linefeeds inside "" correctly
- Fixed bug where closing some but not all documents could make TreeSheets confused as to which document it is looking at
- Fixed bug where it could display the wrong filename on tabs/window title due to autosave
- Linux bug related to unicode keystrokes workaround 
- Linux now has wxwidgets 2.9 statically linked, so doesn't require that to be installed anymore

2009-11-05:
- You can now change both the color and width of grid borders
- Added fullscreen toggle (F11), and scaling toggle (F12): useful for presentations.
  TreeSheets can do better presentations than powerpoint this way, as you can structure your presentation
  around hierarchical zooming, which is much more coherent than a sequential set of slides
- HTML export now sets colors & styles
- HTML/XML/TXT export now always export the current view instead of the entire document (much like image export)
- Now remembers all open files when you re-start TreeSheets
- Added option to show file tabs on the left instead of on top (to save vertical space)
- The "Open link in browser" and "Go to matching cell" functions now also work on text selections rather than just whole cells
- Added SHIFT + Home/End operations for text editing (extends selection)
- improved grid rendering to have a tiny margin
- improved the way it scrolls the selected cell into view if it is partially out of view
- find next (F3) zoom in automatically if cell is too small to read
- Extend Selection to Full Rows/Columns of current selection
- fixed: deleting the top level grid on a zoomed in view would crash
- fixed: cancelling new file dialog would crash treesheets
- fixed: icon did not show in the window frame
- fixed: filenames could get confused when switching tabs
- fixed: text editing in both search controls
- fixed: possible hang in rendering with truely huge treesheets files
- made the automatic text sizing at zoom a bit more reliable
- removed the "remove grid" (CTRL+r), "replace parent" and "merge with parent" (CTRL+m) operations,
  as simply using copy/paste/delete on the cells instead is much more intuitive
- window now de-minimizes from tray if app is launched again or a treesheets file is launched from explorer
- shows filename on "discard changes?" dialog
- updated the tutorial with some recent features, and the spreadsheet language
- shows <unnamed> on new tabs
- linux fixes

2009-06-30:
- Prevents multiple instances being opened, instead files launched will open in the existing instance
- Will notify you if you accidentally try to open the same file
- empty cells are now at least square in size
- shows a "+" instead of a "*" when a file has been modified but has been autosaved
- fixed ENTER stopped working (caused by tabs)
- fixed bug that could cause characters to be missing on a multiline rendering

2009-06-25:
- Multiple documents can now be open in a single TreeSheets instance.
  - Tabs allow you to switch between them.
  - copy/paste between seperate files within the same instance of TreeSheets now retain layout and images faithfully.
- Search functionality:
  - CTRL+F focuses on search box
  - press F3 to cycle through all search results
  - Replace box, type text in here, and then use:
    - Replace All to replace all occurrences of the current search
    - Replace in Current Selection: either work in combination with F3 to selectively replace search results,
      or you can even select a hierarchical subset of all search results and then replace all in that.
- autosave: saves files that have unsaved modifications to a .tmp whenever the file hasn't been saved for 5 minutes,
  you go idle for 1 minute, you minimize or deactivate the window, whichever comes first. This file gets removed if you do an explicit save,
  and you can restore it should your machine crash (TreeSheets will ask you). Does not activate for "new" files that have never been saved before.
- made multi-cell Paste (and Merge with Parent) not insert unnecessary cells when blank cells are available at the target location
- added "Minimize to Tray" option
- added Sort operation: make a 1xN to indicate what column to sort on, and what rows to affect
- drag & drop of files now works, currently only image files supported (anything else appears as the filename). May support other formats in the future.
- added seperate XML with attributes import mode (for formats that store their data there, like OPML)
- CTRL+SHIFT+cursor left & right now select words at a time in edit mode (much like any text editor)
- automatically increases the number of lines in a cell if text insertions cause it to go over N characters average, configurable from the menu.
- fixed status bar not updating when changing text size on a cell
- you can now undo past the point of your last save, all the way to how you loaded it
- added menu option to disable writing of .bak files on save
- "Set Print Scale" allows simplistic scaling of print output. No multi-page output yet.
- fixed image export not clearing background correctly
- fixed tutorial file not being added to the file history correctly

2009-04-26:
- fixed thin selections not centering on zoom
- fixed cursor keys & tab on linux

2009-04-25:
- can now copy/paste and drag&drop images and text directly from other apps into a treesheet (e.g. web browser, photoshop, etc).
- you can now select a custom color, and assign it to cells from the color menu
- improved color/style picking for new rows/columns inserted
- automatically scrolls & zooms out to bring the current selection in view for most operations (keyboard movement, etc).
- optimized the screen refreshing
- when copying a single cell, now properly remembers number of lines, color/style
- ENTER on grid line selections now inserts a cell
- SHIFT+leftmouse now enlarges the selection, same as if you had dragged to that location.
- Export current view as PNG file
- fixed bug in printer scaling
- made mousewheel accumulative, to hopefully make zooming work better on continuous mousewheels.

2009-04-19:
- Added "Go To Matching Cell" (F6) function: will select whatever cell has the same text. If multiple other cells are
  available, will prefer to go to a cell that has different formatting (color/style) than the current cell (this is
  to allow this feature to be used as specially marked "links" to a reference cell).
- as a temporary solution, added a "simple rendering mode" that does not make use of XOR to show selections, and
  thus renders correctly on on MaxOSX and Linux. It is slower to refresh and does not give hovering feedback, but at
  least it works. More advanced rendering on these platforms will have to wait until wxWidgets supports wxOverlay's
  with blending.
- fixed several issues where the linux version of the wxWidgets behaves differently
- Made some improvements to make the UI more compliant on the Mac (about/exit menus, drag & drop, some shortcuts)
- fixed crash bug related to right-clicking outside the treesheet
- added a "traditional mousewheel" option that swaps the zoom & scroll functions
- removed the floating grey cursor (it was confusing)
- the text cursor is now a blinking black line (as in Excel)

2009-04-02:
- XML export now writes text size/color/style information
- XML import now recognizes its own XML code (grid sizes, text size/color/style), thus can reconstruct a treesheets file 1:1
- rewrote the line splitting algorithm to allow more characters to be the splitting point
- rewrote the column resizing algorithm to work more accurately
- Added semi-colon CSV format as an alternative to comma CSV import
- ESC now selects the parent cell of the current selection if not in text edit mode, and SHIFT+ENTER selects the first child
- added underlined style
- no longer creates a new selection if you right-click inside an existing selection
- added keyboard shortcuts for text size and line count (CTRL/SHIFT + PGUP/PGDN)
- double clicking the current color assigns it directly to the selection, as intended
- fixed line rendering bug when using colored grids

2009-03-20:
- every cell can now have its own background and text color
- shows an edit mouse cursor in text edit mode
- made ctrl+p mean print rather than replace parent
- created work-around for cursor left/right & delete not working in the search box
- fixed bug in Undo coalescing that could cause crash

2009-02-27:
- automated column resizing! SHIFT+mousewheel now finds the widest (or thinnest) cell in a column instead of just resizing the current cell.
  Even works on multiple columns at once or hierarchically.
- added CSV (comma seperated values, for use with Excel), tab delimited text and indented text as import options
- added outline html export, which loads into Word as an hierarchical set of headers
- Search box in the toolbar: shows all text that matches the search in red. May add more featureful search & replace in the future
- ALT + cursor keys or mousewheel scrolls the view
- Undo undoes all edits in a single cell all at once, and ESC is the same as Undo + leave text mode, when in text mode (just like Excel)
- Select all (CTRL+a) expands the current selection to the entire grid it is in
- shift+tab goes to previous cell
- added "launch in browser" for cells with urls in them (F5)
- added F2 (rename in my many apps) as an alternative to ENTER to enter text edit mode
- fixed bug where backspace wouldn't delete entire cell selection
- fixed unusued special keys (such as F1) showing up as random characters

2009-02-24:
- doubleclick to select a word (when already in text edit mode), and doubleclick+drag to select a range of words
- TAB now advanced to the next cell (to the right, or down, or back again to the top) and also selects its contents in text mode.
- Any cell can now have a "style", sofar available: bold/italic/typewriter
- increased maximum font size
- fixed XML export doctype

2009-02-20:
- initial "polished" release (history below this point deleted)

2009-01-25:
- initial public release

2009-01-19:
- closed beta release