toggle aura with a custom SecureActionButtonTemplate button (like Stancebar)

[sezz]

i want to recreate the hunter aspect bar for wod using custom buttons based on SecureActionButtonTemplate

currently i'm using this to cast a spell on left click and cancel the aura on rightclick:

button:SetAttribute("type", "spell");
button:SetAttribute("spell", spellId);
button:SetAttribute("type2", "cancelaura");
button:SetAttribute("unit2", "player");
button:SetAttribute("spell2", spellName);
button:RegisterForClicks("AnyUp");

is there a way to change the behavior of my buttons to act more like the real stancebar, that means left click should cancel the aura if it is already active and casts it if not?