[Customdrawn] Replace some widgets

[Michael Schnell]

I understand that CustomDrawn provides code for rendering the visual 
"Components" (Widgets) used by the user code to pixel-images. Same are 
then sent to one of the attachable backends to have them displayed.

Now these Components not only need to be visualized, but they also 
provide information to the user code (events, readable properties, ...) .

I understand that there are "basic" Components (supposedly something 
similar to Panel and Label) that in fact need to be rendered and "higher 
level" Components that use the basic ones to have themselves be displayed.

If I decide that some or all of these "basic" components should not be 
rendered to pixels but still the user code needs the functionality it 
sees: does the CustomDrawn code provide a "hook" that allows for 
replacing the pixel-rendering code by something provided by a 
"3rd-party" ? (E.g. to create a "remote" GUI or to switch off the 
visibility altogether.)

This of course not only asks for appropriately intercepting the 
information flow direction towards the visualization, but also needs 
allowing to implement the appropriate events (such as those generated by 
Timers and Threads and - if doing a remote GUI - the remote user).

Thanks,
-Michael