You might give these a try...
Micro-Mark Saw Blades
They come in 24, 30, and 40 tpi (teeth-per-inch) and fit a standard #11 blade holder...very handy. The other nice thing is that they cut on the pull stroke (Japanese style of saw blade) which I find gives excellent control.
About 1/8" dia. hole in two diagonally opposite corners will get you started for a window hole.
Which reminds me...time to make a tool order for several items...these included!