Two things that can be irritating with UMG are widgets getting in the way of other widgets, and being unable to see all of the content in a scrollbox. My suggestions :
Allow widgets to be hidden in the editor. Sometimes you want to have nested menus which are hidden in game until you go through the menus. In the editor however, they are always visible and obscure your ability to edit the widgets behind it.
Be able to use the scroll bar for scroll boxes in the editor, as well as in the game - allowing for easier editing of the items inside the scroll box.
Press the eye beside the items in the hierarchy view you’d like hidden at editor time.
Maybe one day, not any time soon. What situation are you encountering where you need to place a ton of items in a scrollbox at design time? Normally the scrollbox is reserved for data driven dynamic displays, and it’s not expected that a user would need to fill them with tons of data / widgets they know can’t fit in the space allocated at design time.
I can’t speak to his situation but I currently keep my various gameplay options nested in scroll box columns; e.g. Audio, Visual, Control, etc. and each column has a scroll box which contains, vertically, all of the options of that category.
Given the way my menu widgets are set up it’s not super difficult for me to just temporarily expand the scroll box size down to some extreme degree to see all of the stuff, make changes, and then revert its vertical bounds to their proper size… but I can see why that might irritate some people.