The program contains a number of settings and options to help the search for a solution, and if required, to avoid mistakes. The "Set help level" option in the File menu gives access to three levels of checking that the program can perform to monitor the actions of the user: "Highlight inconsistencies", "Highlight wrong answers", or "No help".
The Highlight inconsistencies option in the File menu sets the program in a mode in which it will constantly monitor the state of the grid to check for inconsistencies. What does it check for? A) count the remaining cells in each strip, calculate the remaining sum for the strip: is this a legal cell count and sum? B) For each cell: is the guess not set but all the candidates have been removed? C) For each strip check to see if any guesses are duplicated. D) For each strip, can the remaining candidates be arranged to give the required sum? This last check slows the program down as, at present, it requires calculating the permutations for all the possible combinations. For that reason it is only applied once immediately after the user has selected the option. From then on only the other checks are continually performed.
If any inconsistencies are found the offending cells will be given a red background.
If the grid is found to be inconsistent the "<<" button in the Toolbar will step backwards through each preceeding grid state until the inconsistency is not present.
The Highlight wrong answers option in the File menu sets the program in a mode in which it will constantly monitor the state of the grid to check for cells set to the wrong symbol. If any are found the offending cell will be given a red background as shown in Figure 1.
When a puzzle is complete it has zero information content. On the scale used by SourGumdropK, a completely empty grid has information content of 9 * number_of_cells_to_solve, 9 being the information content for a completely unfiltered cell. Each time a candidate is removed from consideration the information content reduces by 1.
The total information for a cell is shown at the bottom of the program display with the heading "Info". It can be used to gauge the number of steps still required to finish the puzzle.
As a guide to the user, the information for each cell is shown by the colour of the large button at its centre: the colour gets lighter as the number of candidates is reduced. The current range of shades is shown in Figure 2.
Note that display of these colour codes can be switched off using the "Set/Unset info colouring" option in the File menu. When switched off the display appears as shown in Figure 3.
SourGumdropK can reveal the solution for individual cells or for the whole grid. To see the solution for an individual cell use the option "Show solution" in the cell's menu (left click on the big button). This increments the program's history by 1 and can be unset using the "Undo" command/button. To see the solution for the whole puzzle use the option "Show solution" in the File menu. This increments the program's history by 1 and can be unset using the Undo command/button.