Without a screenshot to be sure, I'm guessing the dashed line you're talking about -- it would be a dashed line rectangle -- is called the bounding box. It will show up around whatever object you've selected.
The canvas is the entire drawing area, whether it's inside the page border or outside. (The page border is a solid line rectangle, and can have a shadow and can be hidden, if you like.)
Hhmm, these on canvas controls must not be in my version of 1.0 alpha. I'll have to download a more current version to test and try to answer your question.
Personally, I wouldn't file a bug report until we're sure everyone is talking about the same thing.... I can download later tonight, and then I'll post again, after I've tested.
However, I would echo my last comments, and hope that they can fix the problem, rather than add some new feature to control the problem.