How involved was Akira Toriyama in the production of Dragon Ball GT? I always had this doubt about whether Dragon Ball GT was an official, canonical sequel of Dragon Ball Z or not. I know that Akira Toriyama helped in the development, but did he write any of it?
Dragonball GT was not made by fans. It was made by Toei Animation with involvement from Akira Toriyama. According to this wiki, his involvement is outlined as:


  Akira Toriyama is credited as author in the ending credits of Dragon
  Ball GT; he oversaw the series' production, this was the same process
  that was used during the production of the anime series Dragon Ball
  and Dragon Ball Z. He drew a rough design for the GT logo, he designed
  the GT appearance of the series main cast, and he designed the
  appearances of Giru and the GT spaceship used in the Black Star Dragon
  Ball Saga. He also drew at least three color pictures of Goku, Pan,
  and Trunks adventuring on various planets (Monmaasu, Rudeeze, and an
  area in Hell).
  
  Toriyama seems to have positive feelings towards his works'
  continuation, as he drew his own version of Super Saiyan 4 Goku (which
  was originally designed by Katsuyoshi Nakatsuru) exclusively for the
  Dragon Box GT. Characters and events from GT have also been included
  in more recent Dragon Ball video games.