Tool tip: in case I'm not the last person to figure this one out! I FINALLY discovered, by accident, that if you press Shift-Click you can decorate the walls and floors in a room with a single click. OK, 2. One for the floors, one for the walls ... Call me extremely slow, but I thought I'd share in case others are still placing each #8*()! piece of wallpaper one square at a time. Hey, wonder if it works with hedges ... hmmmm ...
You can undecorate them quickly, too, by ctrl-shift-click. You get some money back (not as much as the stuff cost.) Minor side note for those starting out: you can't remove tiles from under objects on floors #2 and above. I generally move the furniture out of the house if I'm redecorating. So's I can get a little money back, of course, from those tiles under the tub and toilet, etc.
Poor SBW, Did you not notice that if you select one of the wallpapers a description comes up, and after each description of each wallpaper it tells you about the Shift-Click shortcut? =) But, "better late than never" is one of the sayings I live by, so hopefully others will learn of this time saver as well!
