Is there an example for an application based on Eclipse RCP that does not look like an engineering tool, but is more friendly to ordinary users, so I could learn from it (the preferred option is open source)?
A great example of what is possible with Eclipse RCP is Lotus Notes 8 :
I'm not sure how they adapted the user interface, but suggested that they used the presentation API and did some manual SWT work.
Eclipse Riena. :
... Riena , -, , workbench .
, :
CSS, Eclipse 4 ( e4) . !
!