templates.xml

<Ui xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://www.blizzard.com/wow/ui/" xsi:schemaLocation="http://www.blizzard.com/wow/ui/
https://raw.githubusercontent.com/Gethe/wow-ui-source/live/Interface/FrameXML/UI_shared.xsd">

    <Button name="GTTriStateButtonTemplate" virtual="true">
        <Size x="100" y="26"/>
        <PushedTextOffset x="0" y="0"/>
        <KeyValues>
			<KeyValue key="checked" value="0" type="number"/>
		</KeyValues>
        <Layers>
            <Layer level="BORDER" textureSubLevel="1">
                <Texture parentKey="checkBox" atlas="common-dropdown-ticksquare" useAtlasSize="true">
                    <Anchors>
						<Anchor point="LEFT"/>
					</Anchors>
                </Texture>
                <Texture parentKey="icon">
                    <Size x="24" y="24"/>
                    <Anchors>
                        <Anchor point="LEFT" relativeKey="$parent.checkBox" relativePoint="RIGHT" x="7" y="1"/>
                    </Anchors>
                </Texture>
            </Layer>
            <Layer level="BORDER" textureSubLevel="2">
                <Texture parentKey="iconBorder">
                    <Anchors>
                        <Anchor point="TOPLEFT" relativeKey="$parent.icon"/>
                        <Anchor point="BOTTOMRIGHT" relativeKey="$parent.icon"/>
                    </Anchors>
                </Texture>
            </Layer>
        </Layers>
        <ButtonText parentKey="text" justifyH="LEFT" wordwrap="false">
            <FontHeight val="26"/>
			<Anchors>
				<Anchor point="LEFT" relativeKey="$parent.icon" relativePoint="RIGHT" x="7" y="1"/>
			</Anchors>
		</ButtonText>
        <NormalFont style="GameFontHighlight"/>
        <HighlightTexture parentKey="HighlightTexture" file="Interface/QuestFrame/UI-QuestTitleHighlight" setAllPoints="true" alphaMode="ADD"/>
    </Button>
</Ui>