I have seen this has been asked before. As i suppose the devs dont read every single post in this forum i decided to open a new thread on it (the post is a year old). Try to sell your excess of the crafting tools you collected multiple times and keep the last one - not possible to my knowledge. shift-right-click to divide stacks into different portions or at least sell one by one would be nice.
Also, we still need a button to unstack things. There's still a lot of things that can't be done with the mouse, I'd like to be able to do this stuff using just the mouse.