Until they expired, Apple offered licensing of these patents. Microsoft had access to Apple's TrueType patents through cross-licensing. These patents have proven problematic to developers and vendors of open source software for TrueType rendering, such as FreeType. To avoid infringing on the patents, some software disregarded the hinting information present in fonts, resulting in visual artefacts. FreeType developed an automatic hinting engine, but it is difficult to beat the explicit hinting guidelines provided by the typeface designer. The problem of lacking hinting could also be compensated for by using anti-aliasing, although a combination of the two produces the best result.