I beg your pardon if this is a daft question, but i leaped and installed the Bandcamp Sonar and loaded a tiny project of mine (consisting of some midi-tracks and a pair of VSTs). In X3 (top most image), i have the synth rack clearly visible and accessible (i.e i have "Media", "Plugins" and "Synth".
 
In BC Sonar (lower part), this pane is nowhere to be found (??). I can clearly hear those soft-synths, but can't find them anywhere.
(only see "Media", "Plugins" and "Notes").
 
Is this some expected behaviour that differentiates X3 from Platinum (and BC Sonar)??
 

It is a separate view, look in the Views menu

The Synth Rack got moved out of the standard browser a while ago. It's now got its own panel. Go to the menu item Views > Synth Rack View, or press Alt+9 to turn it on.

Dang :-D
 
NOW i see it. But the actual synth rack is moved out onto its own pane now... (used to be a combined one). 
 
Thx again scook and John

It may be added to the Browser, just not as a tab. There is also a help module in views that works the same way in the browser. The old SONAR help is still up. You may find it useful to navigate the changes since X3. BandLab is working on porting the help system.

Caught me out, too!