[Xrystal]

Spotted this with a general search for PickupSpell. It's in the SpellBookFrame.lua file from the new API files you can download from the wow site.

PickupSpellBookItem(slot, SpellBookFrame.bookType);

Here is the whole function in its entirety.

function SpellButton_OnModifiedClick(self, button) 
	local slot = SpellBook_GetSpellBookSlot(self);
	if ( slot > MAX_SPELLS ) then
		return;
	end
	if ( IsModifiedClick("CHATLINK") ) then
		if ( MacroFrame and MacroFrame:IsShown() ) then
			local spellName, subSpellName = GetSpellBookItemName(slot, SpellBookFrame.bookType);
			if ( spellName and not IsPassiveSpell(slot, SpellBookFrame.bookType) ) then
				if ( subSpellName and (strlen(subSpellName) > 0) ) then
					ChatEdit_InsertLink(spellName.."("..subSpellName..")");
				else
					ChatEdit_InsertLink(spellName);
				end
			end
			return;
		else
			local spellLink, tradeSkillLink = GetSpellLink(slot, SpellBookFrame.bookType);
			if ( tradeSkillLink ) then
				ChatEdit_InsertLink(tradeSkillLink);
			elseif ( spellLink ) then
				ChatEdit_InsertLink(spellLink);
			end
			return;
		end
	end
	if ( IsModifiedClick("PICKUPACTION") ) then
		PickupSpellBookItem(slot, SpellBookFrame.bookType);
		return;
	end
	if ( IsModifiedClick("SELFCAST") ) then
		CastSpell(slot, SpellBookFrame.bookType, true);
		SpellButton_UpdateSelection(self);
		return;
	end
end