Mine Sweeper Clone

I created this simple Mine Sweeper game for a tutorial blog post I wrote at: https://rookj.blogspot.com/2019/09/tutorial-making-minesweeper-game.html

You can find the source code here: https://pastebin.com/Uux37M2P

The artwork I used can be found here:

music icon - https://publicdomainvectors.org/en/free-clipart/Eighth-musical-note-vector-image...
flag icon - https://publicdomainvectors.org/en/free-clipart/Red-racing-flag/48786.html
bomb icon - https://publicdomainvectors.org/en/free-clipart/Shiny-bomb-with-lighted-fuse/358...
clock icon - https://publicdomainvectors.org/en/free-clipart/Clock-silhouette/53143.html

I welcome any constructive feedback.