[b]Proposition:[/b][i] Trim objects to a viewport (panel, context menu, etc).[/i]
PanelCircle[A, r, P, w, h]
[math] \;\;\;[/math]Circle with center A and radius r.
[math] \;\;\;[/math]Panel with bottom left corner P, dimensions (w × h).
Example and construction: [url]http://www.geogebratube.org/material/show/id/94541[/url]