It is very slow to drag blocks and split them up while crafting and just generally in inventory. I cannot just hover a stack over two slots to split it in two, rather, I have to right click and drag. For bigger projects this takes up a lot of time and is very slow. 

The same issue happens with crafting-- for example, as shown in the video below, a stack of wood logs cannot be crafted into stacks of planks all at once. I have to drag each batch of four separately, but sometimes that batch of four changes into an irregular number, like 12 or 16, randomly. 

I am not sure why this occurs, but I hope this makes sense and can be fixed!

(vid attached to help visualize!!)