The Sitefinity page editor supports changing properties of any controls that you add from the toolbox. If you create a user control such as the one you want, you would only be able to change its properties, and not the properties of the Generic Content
inside it. This in fact means that you have to create custom logic to be able to edit those Generic Content
controls in RadEditor.
I'm not really sure what is the advantage you are trying to achieve through this implementation. If the only reason for doing this is UI (how these GC
s are rendered on the page), then you can create a nested masterpage which would contain those 2 Generic Content
controls and include the static markup in the child master, all the rest markup for the page being in the parent master. In this way you would be able to edit both GC
s with RadEditor and the only disadvantage is one more drag-n-drop operation to place the controls on the page.
If you have another reason for using such a user control, then please explain in more detail what you are trying to achieve, so that we can help you better.
the Telerik team