[Ketho]

.. I will try to help then~

You could register for TRAINER_SHOW, and only then maybe use an OnUpdate handler to click on the button, and cancel the OnUpdate handler again on TRAINER_CLOSED. but that's just my 2 cents...

This link should also be useful, for in the future

• AutoTrainSpells.lua

  local f = ClassTrainerTrainButton
  f.e = 0
  
  f:SetScript("OnUpdate", function(f, e)
  	f.e = f.e + e
  	if f.e > .01 then
  		f.e = 0
  		f:Click()
  	end
  end)

• AutoTrainSpells.toc

  ## Interface: 40100
  ## Version: 0.1
  ## Title: AutoTrainSpells
  ## Notes: Auto trains your spells
  ## Author: Xaelic
  ## Dependencies: Blizzard_TrainerUI
  
  AutoTrainSpells.lua