what is the mazimum icon' size can be used in c++ mfc dev?

Question

what is the mazimum icon' size can be used in c++ mfc dev?

Answer 1

256x256 pixels in 24-bit color (which is the largest supported by the .ICO file format).

Edit: at least as of VS 2008, the full list is: 16x16, 32x32, 48x48, 64x64, 96x96, 128x128, and 256x256 pixels. Supported bit depths are 1, 4, 8 and 24 bits per pixel. It does also have a "custom sizes" dialog, in case you want an intermediate size, a non-square proportion, etc. Your choices of bit-depth remain the same though (1, 4, 8 or 24-bits per pixel).