A sudoku solver for use in Tok's Proving Grounds.

Graphical interface:

Left clicking a grid cell highlights the cell as active and enters keyboard input mode.
In input mode, type a digit 1-9 to set the active cell value. Space bar or 0 clears the cell.
To change the active cell, left click another cell or use the arrow keys or AWSD.
To exit input mode, press the Return (or Enter) key.
Right clicking a cell clears it.
When the cursor is over a grid cell, the scroll wheel can be used to change the cell's value.
Right clicking or using the scroll wheel will end input mode, if it is active.
The SOLVE button searches for a solution that fits the current grid values.
While a solution is displayed, the UNSOLVE button will revert the grid to its prior state.
The RESET button clears the entire grid.
The grid state is persistent between logins.

Text interface:

All addon functionality is available via chat commands. Commands are listed below.
Most commands have one letter abbreviations.
For the value command, the digit may be 0 or omitted to clear the cell.
For the assignment commands (row, column, region), an empty cell is represented by 0 in the digit string, and trailing 0s are not necessary. For example, the following command would set the middle 3 cells of the fourth row: /tokker row 4 000257
Successive commands which directly affect the grid may be combined onto a single line. Commands are separated by commas. The following commands may be combined: row, column, region, value, solve, unsolve, print, reset.
Example: suppose you notice that one of the clues you used to solve a grid is in the wrong cell, all the steps to fix the problem could be combined into one line:
/tokker u, v 2 3, v 2 4 9, s, p

Command list (abbreviation letters are underlined):

/tokker - toggles the Smooth Tokker window open or closed

/tokker row [n] [digits] - fills in row [n] using the string of [digits]

/tokker column [n] [digits] - fills in column [n] using the string of [digits]

/tokker region [n] [digits] - fills in 3x3 region [n] using the string of [digits]

/tokker value [r] [c] [digit] - sets the grid cell with row [r] and column [c] to [digit]

/tokker solve - finds a solution that fits the current grid values

/tokker unsolve - reverts a solved grid to its prior state

/tokker print - prints the grid state to the chat window

/tokker reset - clears the grid

/tokker scale [x] - sets the scale factor for the Smooth Tokker window to [x]

/tokker autoprint - toggles autoprint: when activated, prints the grid state to chat after each command

/tokker help - prints graphical interface usage and further help topics to chat

/tokker help config - prints details on the configuration commands

/tokker help text - prints details on the text interface

/tokker help commands - prints the complete list of chat commands