When you have huge lists of things in UI you often run into a problem of there being way too many panels. It doesn't matter how fast your UI system is, there's always a number of panels that is going to bring it down.
Virtual scrolling solves that by only showing the panels that are visible. As you scroll panels that go out of view are destroyed and panels that come into view are created.
So instead of adding panels to it, you add data to a list. Then you just have to tell it which type of child panel to create.
attribute 'contenteditable' not allowedattribute 'blocktype' not allowed
