That's a really great innovation! One of the most frustrating things in a game of minesweeper is when you are forced to guess and lose through no fault of your own. It's all the more frustrating because it tends to happen late in the game, too. I definitely would enjoy your version more.

Not all implementations suffer from these.

There are some that guarantee that guessing will never be forced to guess and logical deduction is enough to solve any puzzle. For example, the Mines game in Simon Tatham's Portable Puzzle Collection.

Another improvement would be to auto clear adjacent squares when marking a mine.

If I marked as mine, and it is surrounded by the number 1, I would like all squares that neighbors those to be cleared automatically.

It could be triggered by double clicking the flag.

It is rare that you want to clear all the tiles that neighbors a flag itself.

Usually you want to clear all tiles that touches, let say a "1" that is already touching a flag, and you can do just that by clicking that "1".