Handling "OnShow" frame event

Hello,

I created a frame template using XML code

<Frame name="FrameTemplate" virtual="true">
<Scripts>
<OnShow>
print('Hello World')
</OnShow>
</Scripts>
</Frame>

Now I can create new frames in Lua using this template

local frame = CreateFrame("Frame", "NewFrameTemplate", UIParent, "FrameTemplate")
frame:SetSize(100, 100)
frame:SetPoint("CENTER")

If I write

frame:SetScript("OnShow", function() print('Howday?') end)

Every time the frame is shown, 'Howday?' will appear, but no longer 'Hello World'.
Is there a method, in the 3.3.5a client, to ensure that the script present inside the <OnShow> tag is not overwritten?

Yes, use HookScript instead.