Dear Diederik,
Thanks so much for taking the time to reply (see below).
Indeed, it should be indicated somewhere which snap mode is active. I'd prefer to go the status bar route though, because I don't think it's important enough to display it near the cursor. Besides, showing it at the status bar is the easiest thing to implement. Please file an RFE for this in Launchpad and assign it to me.
I was thinking of the status bar giving a quick indication of which snap modes (insersection, quadrant) are currently globally turned on, since several could be on at once. A single keypress could then visually turn each off at once without loading the document properties tab.
To indicate the current snap as a line is drawn I was thinking of something either floating next to the cursor, or the shape of the cursor changing as it jumps when you are drawing a line and come within a 'snap radius' of an active snapping point (as Johan said).
I think it would be important to indicate to the user in some way whether the system thinks it's currently snapping to a gridpoint or an endpoint if two are nearby and both types of snap are turned on at once.
I've found the following page online with a few screenshots showing corel draw - if you scroll to the bottom of the page and see the image before last. As you see corel shows the type of snap as a line is drawn by the shape of the cursor, and by the floating 'help' message.
http://www.cadintools.com/cdr_tips.htm
I'm not sure that I fully understand what you're trying to explain here: what do you mean with "center of a translation"?
To explain what I was meaning, if you take a look at the final screenshot on the same page:
http://www.cadintools.com/cdr_tips.htm
In this they want to move (translate) the rectange from the upper left position so that it ends up just touching the circle. With the snap enabled as they click to select the rectangle they can pick it up _from_ the midpoint of the right side (so that is where they are 'holding it' as they move) and then release when this point is caught by the quadrant snap of the circle. This guarantees the rectange and circle are perfectly aligned and touching, and applies to all types of snap. When I said 'centre of translation' I was meaning the midpoint of the right side of this rectange in this case, and this centre can be selecting using all possible snap points of an object or group of objects.
I hope that makes what I was meaning clearer ?
I agree with Shawn that with multiple grids possible the on/off snap is a property of each which I hadn't though of before!
Thanks for your time Diederik and for the patience to listen again - I;d lvoe to hear any comments :-)
Alex