Worth noting that some custom icons, especially older ones, might not work with the current version of Warcraft III due to changes in the BLP code. If the BLP files were correct this would not be a problem, however as far as I know there are no correct user made icons as there were no correct BLP tools to make them. Most should still work due to being vaguely right, however some made with older BLP tools or without obeying not so silly superstitions will not work anymore.
Specifically this applies to icons which are JPEG content BLP files and were declared as having mipmaps but have an incomplete or broken set of mipmap images. The old behaviour was that broken mipmap images were loaded as transparent black with the texture successfully loading. The new behaviour is that broken mipmap images cause the texture to fail to load.
Tools like BLP Lab automatically "fake" mipmaps by linking to an existing mipmap image (wrong dimensions however it is subject to padding/cropping so ok) so icons made with it should not have any problems. However some older tools, or BLP Lab if set wrong, did not fill all required mipmap levels with working mipmap images so icons made in such a way will fail to load now. Such broken icons can often be fixed by re-converting them to BLP files.
It is also worth noting that icons do not need mipmaps to work, a feature that exists but is not supported by most BLP tools (I think my Java plugin is the only BLP writer to support it). However if they do not have mipmaps they will appear to not load if non-high textures are used (lowest mipmap level is skipped). This is why all Blizzard icons have mipmaps.
Why am I mentioning all this? Well a lot of the icons on this site are very old. Although they have almost all been tested for working, they have not been tested for working recently.
