Great work !
There's one thing I didn't like about it: it refreshes my entire page if I change the component selection or enter a new component. AFAICS this is easy to change: replace the wrapping
by a xp:panel, give it an ID, change the "Server options" for both the "componentId" combobox and "expression" input field to "Partial Update" and select the panel's ID in the "Select Element…" dialog.
Mark