The hierarchy is: I have a kind of root-widget that all other UserWidget-derived widgets are either a part of, or they get dynamically attached to and removed from a panel of it. The root-panel of everything is a canvas in this root-widget. Like I described in the original question, I was hoping I could stop my context menus from being partly off-screen when clicking near the right or bottom edge by using the panel’s “Clipping” property. They are rather small, not full screen. I don’t know how to use anchors dynamically. The only function I found related to anchors was “Set Anchors In Viewport” and I’m not sure how to use it.
… and you probably saw my name here : Widget out of screen when opened with an event - Blueprint Visual Scripting - Unreal Engine Forums