Canvass-work area options to lock accidental shifting?

I do not see any way to lock the canvass or work area/page
from shifting off the "corner angle points" that line up
the canvass. Maybe i'm missing something, yet
I don't think the "page and layers gallery" can do this.

In other words, if you you shift the screen, (when you hold down
one mouse key and scroll the canvass, i.e. the white background
or whatever color you use that you put text or graphics
on, shifts off center, especially when you have a thin line boarder
surrounding it or line on one side,-and it shifts-then you
have to line-up or center all the graphics again. Also wonder
if this is an added feature on Web Designer pro/7 ?
Thanks for any and all input.

Have you unlocked the page background layer?

Big thanks, I am a little new to WD6 and was missing
to see the "page background" line in the
'page and layer gallery-Yes, it has lock and unlock
options, everything working great.