Add a tab to MailFrame

[doumakes]

I'm trying to write a mod (my first) that will put a new tab on the mail frame. Feels like I'm getting close, but I could use a few clues to push me forward.

Reading the tabbed windows howto gave me some ideas, but it's awfully sketchy. I've created a frame, I am able to make MailFrame the parent of my frame, I can get my frame to display (in a really ugly cheesy way) when I run MailFrame:Show(). But my tab button doesn't show.

Here's the XML:

<Ui xmlns="http://www.blizzard.com/wow/ui/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.blizzard.com/wow/ui/ C:\Projects\WoW\Bin\Interface\FrameXML\UI.xsd">

<Script file="foo_client.lua"/>

<Frame name="foo_frame_template" hidden="false" virtual="true" parent="MailFrame">
	<Size>
		<AbsDimension x="250" y="250"/>
	</Size>

	<Anchors>
		<Anchor point="CENTER"/>
	</Anchors>

	<Backdrop name="$parentBackdrop" bgFile="Interface\DialogFrame\UI-DialogBox-Background"
		edgeFile="Interface\DialogFrame\UI-DialogBox-Border" tile="true">
		<EdgeSize>
			<AbsValue val="16"/>
		</EdgeSize>
		<TileSize>
			<AbsValue val="32"/>
		</TileSize>
		<BackgroundInsets>
			<AbsInset left="5" right="5" top="5" bottom="5"/>
		</BackgroundInsets>
	</Backdrop>

	<Layers>
		<Layer level="BACKGROUND">
			<Texture name="$parent_Background" setAllPoints="true">
			<!-- Texture has blue color with 50% alpha -->
			<Color r="0" g="0" b="1" a="0.5" />
			</Texture>
		</Layer>
	</Layers> 

</Frame>

<Frame name="foo_client_frame" inherits="foo_frame_template">

	<Layers>
		<Layer level="ARTWORK">
			<FontString name="$parent_Text" inherits="GameFontNormal" justifyH="LEFT" 
				text="Just some text" nonspacewrap="false" maxLines="3">
				<Anchors>
					<Anchor point="LEFT" relativePoint="TOPLEFT" relativeTo="$parent_Text">
						<Offset>
							<AbsDimension x="0" y="-34"/>
						</Offset>
					</Anchor>
				</Anchors>
				<Color r="1" g="1" b="1" a="1" />  <!-- White Color -->
			</FontString>
		</Layer>
	</Layers> 

	<Frames>
		<Button name="$parent_Button" hidden="false" inherits="MailFrameTabButtonTemplate" text="Hello" id="3">
			<Anchors>
				<Anchor point="BOTTOMRIGHT" relativeTo="$parent" />
			</Anchors>
			<Scripts>
				<OnClick>
					Button_OnClick( arg1 );
				</OnClick>
			</Scripts>
		</Button>
	</Frames>

	<Scripts>
		<OnLoad>
       		this:RegisterEvent("VARIABLES_LOADED");
		</OnLoad>

		<OnEvent>
			if ( event == "VARIABLES_LOADED" ) then 
           		foo_client_init();
            end 
		</OnEvent>
	</Scripts>

</Frame>

</Ui>

And here's the LUA:

MY_VERSION = "0.2"
MY_FONT_COLOR = { r = 0, g = 255, b = 0 };

--
-- foo_client_init()
--
function foo_client_init()

-- Create slash commands
SlashCmdList["FOO"] = foo_client_command;
SLASH_FOO1 = "/foobar"
SLASH_FOO2 = "/foo"


-- Register for drag-and-drop.
this:RegisterForDrag("LeftButton");

-- Announce success.
DEFAULT_CHAT_FRAME:AddMessage( "Addon-with-no-name version "..MY_VERSION.." loaded", 
	MY_FONT_COLOR.r, MY_FONT_COLOR.g, MY_FONT_COLOR.b );

end


--
-- foo_client_command
--
function foo_client_command( msg )
	
local frame = getglobal( "foo_client_frame" )
if (frame) then
	if (  frame:IsVisible() ) then
		frame:Hide();
	else
		frame:Show();
	end
end

end