Required icons sizes

Unless I missed something, these are the sizes that may be required by the OS from a Windows app icon.

16, 32, 48, 256 are more or less expected. These are small, icon, tile and extra-large views in Windows Explorer.

20, 22 and 26 are possible sizes of an icon used in the window caption. Depending on the configured DPI level.

And 40 is the size of an icon used in Alt-Tab view on W7.

If you don't provide an appropriately sized icon, the OS will grab one that is slightly bigger and shrink it down. "You are welcome, here's your pixel poop" kind of thing.

Now, let's also not forget that each icon should ideally be saved in 3 color depths - 32, 8 and 4 bits. All summed up, this particular .ico file weighs about 120KB, whereas the actual application code that does quite a few meaningful things currently sits at 96KB. So, yeah ... o_O