snap only to visible grid

[CookieEater200]

Hello  ,

I like to put rectangles and have the corners snap only to visible lines. I have looked at View->Visual aids->General and put a check in the currently active snap and the snap to grid. When I drag rectangles around, I can leave them on locations that arethe grid lines and also locations that are not the grid lines. Is there a way to make it go only on the grid lines?

Also, the quantity of grid lines change as I zoom in and out. Is there a way to force them to be always the same distance in mm apart?

Thanks