Weird behaviour with unstackables being stacked (reopened)

You can pick up an item that is above it's max stacking limit, such as a sword stacked to 64, which is clicked with another stack, and this causes the stack to increase higher, 

This issue is for all overstacked items, such as 32 enderpearls, 64 totems etc.

(The screenshot is from another launcher, but it shows the same point.)