The UIR editor does not permit you to create a panel inside an existing panel, you must do it a load time instead. The trick is to pass a valid panel handle in the first parametere of the function; as you ca read in the online help;
| parentPanelHandle |
integer |
Handle of the panel into which to load the panel as a child panel. Pass 0 to
load the panel as a top-level window. |
Take a look at \userint\panels.prj for an example on how to create and treat child panels.
