You will need to be patched to 1.26-1.42 to use this.

What it does...
For Base Game...
This mod adds an "Open" and "Close" interaction to the "Stray" and "Window of Opportunity" windows, so sims(YA and up) can open and close them. Just click on the window select "Open", and the sim will walk over to the window and open it. Click on the window and select "Close", and the sim will walk over to it and close it. This was done by adding custom animations I made in Blender, a new script class, and a custom JAZZ script.

Click here to see the mod in action(links to youtube video)

Installation...
Install in your mods folder as usual. This mod may conflict with mods that alter the default MLOD, MODL, VPXY, RIG, or OBJK; basically any default replacements of these windows, including my previous open window mod. You will also need to sell windows already in-game and re-buy them to get the interactions.

"I put it in my game but I get 'No interactions available'..."
If you click on the windows in the game, but can't use it due to the "No interactions available" issue, take a good long look at Game Help:Installing Sims 3 Package Files/Old Way to New Way

updated 11-10-11:
-renumbered rig to fix conflicts/ game freeze bug

Additional Credits:
Thanks to Orangemittens, Jynx, Wes Howe, Atavera, and Inge and Peter Jones.