Hello there Annemarie,
I have some good news. We have just released a new version of Yard Sale Hidden Treasures: Sunnyville - Mac. It has some patches applied to it and it may have fixed your issue if it was a bug.
Uninstall and Reinstall
http://www.bigfishgames.com/help/index.html?rn=492
Uninstalling a game.
Before you reinstall a purchased game, make sure you've uninstalled any previously downloaded versions. To uninstall a game click the “trash can” icon next to the title in your game manager.
Reinstalling a game.
1. Log In to your account.
2. Go to http://www.bigfishgames.com/download-games/4840/mac/yard-sale-hidden-treasures-sunnyville/index.html
3. Download Yard Sale Hidden Treasures: Sunnyville - Mac by clicking the button "Download."
4. Select to "Run" or "open" the file.
Now, holding Ctrl + Clicking will rotate the piece!
Please let me know if the problem continues, and I will be glad to help you until you can play this game with no problems.
Sincerely,
Lenny