Why SetAllPoints?

[hsammyw]

I am trying to understand why I need to use SetAllPoints when creating a button in lua without a template vs with one. Here is the code that I'm using.

local myButton1 = CreateFrame("Button", "TestButton1", UIParent)
myButton1:SetSize(64, 64)
myButton1:SetPoint("TOP", 32, 0)
myButton1.icon = myButton1:CreateTexture("$parentIconTexture", "BORDER")
myButton1.icon:SetTexture("Interface\\ICONS\\INV_Misc_Fish_58")
myButton1.icon:SetAllPoints() -- why?
 
local myButton2 = CreateFrame("Button", "TestButton2", UIParent, "TestButtonTemplate")
myButton2:SetSize(64, 64)
myButton2:SetPoint("TOP", -32, 0)
myButton2.icon:SetTexture("Interface\\ICONS\\INV_Misc_Fish_57")

<Button name="TestButtonTemplate" virtual="true">
  <Layers>
    <Layer level="BORDER">
      <Texture name="$parentIconTexture" parentKey="icon"/>
    </Layer>
  </Layers>
</Button>

You can see that I have to use(?) SetAllPoints in order for the texture to show up. What's the reason?

Thanks!

[MunkDev]

Using XML, the points of a region are automatically matched to its parent unless you specify size and anchor. In plain lua, you're just creating a texture region without specifying where to draw it.

[hsammyw]

I see! Thanks a ton. =)