A delegate which gets called when the font texture is rebuilt (dynamic fonts only).
Note: You should only ever need to use this when you want to implement your own text rendering. When characters are added to the font texture of a dynamic font (by Unity's text rendering system or when calling RequestCharactersInTexture), the texture may not have enough space to fit all characters. When that happens, the font texture gets rebuilt, and previous character postions are no longer valid. Existing meshes using the font will have to be rebuilt to match the texture. You can set up a callback using the textureRebuildCallback property to be notified when that happens.
See Also: RequestCharactersInTexture, GetCharacterInfo.