Looks like Gimp 2.8 to me and in multi-window mode
Keep the tools / tool options away from the canvas otherwise it is active and pressing keys looks like a keyboard shortcut.
Even better, put Gimp into single window mode.
When posting please give Gimp version and operating system, saves on guessing. (OK I see linuxMint but which one ?)
Edit: Something like this https://i.imgur.com/S01deti.mp4
Keep the tools / tool options away from the canvas otherwise it is active and pressing keys looks like a keyboard shortcut.
Even better, put Gimp into single window mode.
When posting please give Gimp version and operating system, saves on guessing. (OK I see linuxMint but which one ?)
Edit: Something like this https://i.imgur.com/S01deti.mp4