What is claimed is:1. An electronic device, comprising:an electronic device housing having openings, wherein each of the openings has a width that is less than 100 microns;light sources mounted within the electronic device housing; andcontrol circuitry that is configured to control the light sources to selectively transmit light through a subset of the openings.2. The electronic device defined in claim 1, wherein the control circuitry is further configured to control the light sources to adjust the subset of the openings through which the light is transmitted.3. The electronic device defined in claim 2, wherein subset of the openings forms an illuminated pattern at a surface of the electronic device housing.4. The electronic device defined in claim 3, wherein the illuminated pattern comprises a control indication pattern.5. The electronic device defined in claim 3, wherein the illuminated pattern comprises a status indication pattern.6. The electronic device defined in claim 1, wherein the subset of the openings forms a circular pattern at a surface of the electronic device housing.7. The electronic device defined in claim 1, wherein the subset of the openings forms a rectangular pattern at a surface of the electronic device housing.8. The electronic device defined in claim 1, wherein the electronic device housing comprises a metal electronic device housing wall that defines the openings.9. The electronic device defined in claim 1, wherein each of light sources transmits the light through a different respective one of the openings.10. The electronic device defined in claim 9, wherein the light sources comprise first and second light sources, the openings comprise first and second openings, the first light source is configured to emit light of a first color that is transmitted through the first opening, and the second light source is configured to emit light of a second color that is different from the first color and that is transmitted through the second opening.11. The electronic device defined in claim 1, wherein the openings comprise first and second openings, the electronic device further comprising:a first filler material in the first opening that transmits light of a first color; anda second filler material in the second opening that transmits light of a second color that is different from the first color.12. An electronic device, comprising:a structure having a surface, wherein the structure defines an opening having a lateral dimension at the surface that is less than 100 microns;a light detector that detects light received through the opening; andcontrol circuitry that receives a control input that is generated based on the light detected by the light detector.13. The electronic device defined in claim 12, wherein the structure comprises an electronic device housing in which the light detector and the control circuitry are mounted.14. The electronic device defined in claim 13, wherein the electronic device housing comprises a metal housing wall and the surface comprises an exterior surface of the metal housing wall.15. The electronic device defined in claim 12, further comprising:a light source that transmits light through the opening.16. The electronic device defined in claim 12, wherein the structure further defines an additional opening having a lateral dimension at the surface that is less than 100 microns, the electronic device further comprising:a light source that transmits light through the additional opening.17. The electronic device defined in claim 16, wherein the opening is configured to transmit light of a first color and the additional opening is configured to transmit light of a second color that is different from the first color.18. The electronic device defined in claim 12, wherein the structure further defines an additional opening having a lateral dimension at the surface that is less than 100 microns, the electronic device further comprising:an additional light detector that detects light received through the additional opening.19. The electronic device defined in claim 18, wherein the opening is configured to transmit light of a first color and the additional opening is configured to transmit light of a second color that is different from the first color.20. An electronic device having opposing first and second sides, the electronic device comprising:a metal housing, wherein the first side of the electronic device has a surface that is defined at least partially by the metal housing;an opaque layer on the second side of the electronic device, wherein the opaque layer defines an opening that is less than 100 microns across; anda light detector mounted within the metal housing that detects light transmitted through the opening.21. The electronic device defined in claim 20, wherein the opening comprises one of a plurality of openings that are defined by the opaque layer and that are each less than 100 microns across, wherein the light detector comprises one of a plurality of light detectors, and wherein each light detector of the plurality of light detectors detects light transmitted through a different respective opening of the plurality of openings.
