When a new UI element is added and it overflows, the only thing that should appear is a scrollbar, and the menu should scroll to the top of the new element so that it is immediately visible to the user.
This will reduce the confusion to why half the UI element they want to look at is cut off, and why everything moved a bunch.
PS:
I dont know what "the message box" is, but dragging dropping files on the text box doesnt work
