Here are my suggestions to make mouse control more fluid (thinking of accessibility here, I remember doomrl getting mouse control down so well, even the ancient/expert players started using it!):

left-clicking a door adjacent to the player should attempt to open it
right-clicking a door adjacent to the player should kick it
clicking on the stairs while standing on them should exit the current level
clicking on an tile should move (1 turn) towards that tile, even if there is a hostile monster nearby
right-clicking on a monster should launch a missile attack at that monster
mouse wheel up and down should scroll menus up and down (this used to work before R48)

(Extra bonus: this is just a nice to have, worth a mention, and not really part of this suggestion for serious discussion unless TB likes the idea:
right-clicking on the player should open a radial gesture menu with spells, inventory, class abilities, special abilities, food eating, skills etc.
Example of a good radial menu in this video: https://www.youtube.com/watch?featur...XIm422DtA#t=52