Thanks for the suggestion. I agree this is useful.
I’ve added a Paint(g As Graphics) event to ContainerControl. It fires when the container is first rendered, when it is resized, and when Refresh() is called.
Painted content appears after BackgroundColour but behind any controls hosted by the container, so it can be used for custom backgrounds, borders, rounded panels, and other decoration.
This will be included in the next release: https://feedback.objo.dev/feature/1334