[Fizzlemizz]

More like:

<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/"> 
    <Script file="Some.lua" />
 
    <Frame name="iTrackerBodyFrameTemplate" virtual="true">
        <Anchors>
            <Anchor point="TOPLEFT" relativeTo="$parent" relativePoint="BOTTOMLEFT"/>
            <Anchor point="TOPRIGHT" relativeTo="$parent" relativePoint="BOTTOMRIGHT"/>
        </Anchors>
        <Backdrop bgFile="Interface\DialogFrame\UI-DialogBox-Background" edgeFile="" tile="true">
            <BackgroundInsets>
                <AbsInset left="0" right="0" top="0" bottom="0" />
            </BackgroundInsets>
            <TileSize val="32" />
            <EdgeSize val="32" />
        </Backdrop>
        <Scripts>
            <OnLoad>
                iTrackerFrame_TitleFrameTemplate_OnLoad_SetWidth(self)
            </OnLoad>
        </Scripts>
    </Frame>
 
    <Frame name="iTrackerFrame_TitleFrameTemplate" virtual="true" movable="true">
        <Size x="200" y="20" />
        <Backdrop bgFile="Interface\DialogFrame\UI-DialogBox-Background-Dark" edgeFile="" tile="true">
            <BackgroundInsets>
                <AbsInset left="0" right="0" top="0" bottom="0" />
            </BackgroundInsets>
            <TileSize val="32" />
            <EdgeSize val="32" />
        </Backdrop>
        <Layers>
            <Layer level="OVERLAY">
                <FontString name="title" parentKey="title" inherits="GameFontNormal" text="&lt;title&gt;">
                    <Anchors>
                        <Anchor point="TOPLEFT" relativeTo="$parent" relativePoint="TOPLEFT" />
                        <Anchor point="BOTTOMRIGHT" relativeTo="$parent" relativePoint="BOTTOMRIGHT" />
                    </Anchors>
                </FontString>
            </Layer>
        </Layers>
        <Frames>
            <Frame name="$parent_BodyFrame" parentKey="body" inherits="iTrackerBodyFrameTemplate" />
        </Frames>
        <Scripts>
            <OnLoad>
                self:EnableMouse(true)
                self:RegisterForDrag("LeftButton")
            </OnLoad>
            <OnDragStart>
                self:StartMoving()
            </OnDragStart>
            <OnDragStop>
                self:StopMovingOrSizing()
            </OnDragStop>
        </Scripts>
    </Frame>
 
    <Frame name="FizzTrack" parent="UIParent"  inherits="iTrackerFrame_TitleFrameTemplate">
        <Anchors>
            <Anchor point="CENTER" relativeTo="UIParent" relativePoint="CENTER" />
        </Anchors>
    </Frame>
</Ui>

function iTrackerFrame_TitleFrameTemplate_OnLoad_SetWidth(Frame)
    -- Set desired height
    title:SetText("Some Name")
    Frame:SetHeight(300)
end

The width of the body will size with the header and its height can be set independently so the function name is now a bit misleading, more like
TrackerFrame_BodyFrameTemplate_OnLoad_SetHeight.

Edited: so the background insets and anchors don't overlay and darken the text.