If you have enough items to get a third row the popup message after purchasing (or attempting to purchase) covers the purchase buttons for items in the center of the screen, requiring the player to wait for the timer to expire on the ui element before they are able to click the purchase button again.  Its mostly an inconvenience but if you want a lot of something in that position you are going to have a bad time.

I modified row 671 (v0.4.67) to adjust the position of the box to "0.33 0.32", "0.67 0.47" so that it is slightly below the center of the screen but only covering item icons in the third row so that the purchase (cost) buttons are still visible and clickable.

Not sure if this is something you want to modify in the official code but at least its here if its bothering anyone else. 

Thanks for sharing your solution. It works great!