I spent some time on my Sudoku program and now I have integrated graphical user interface to it. The menu bar still doesn't work though, so don't try to exit using file -> exit. Anyway, v0.2 is available now in the sidebar.
Brute force search has also been implemented. This means that any puzzle should be solvable now(provided of course, that the puzzle is valid). Of course, given the nature of brute force search, it may take a gadzillion years for the program to find the solution if the puzzle is too hard. So please be gentle on my program :p
I haven't been able to thoroughly test this program yet. So I can't say it's as bug-free as v0.1.