'w' key -> instant crash
 

no more explanation available. every time I push the 'w' key, graffle 6 crashes. repeatedly and unavoidably.

We found out what's causing this crash just recently, it has to do with having Style Brush contents from version 5 copied to the clipboard. If you launch OmniGraffle 5, and click on the Style Brush's drop-down menu and clear the contents, OmniGraffle 6 will no longer crash when selecting the Style Brush (or w on the keyboard, which is the hotkey for that tool). Alternatively, logging out of your user account and back in again clears the contents.

Solution
 

Hooray! It works as described.