Difference between this XML and Lua

[sAlAmAnDeR]

I'm trying to convert some of the code I've already written from XML to Lua, to get rid of the unnessary global variables created and also so I can make a wrapper class which can dynamically create the style of frames that I want. So I have an XML file which looks like this:

<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/
..\FrameXML\UI.xsd">
	<Frame name= "ClassBigFrame" parent="UIParent" toplevel="true" movable="true" hidden="false">
		<Size x="100" y="100"/>
		<Anchors>
			<Anchor point="CENTER"/>
		</Anchors>
		<Backdrop bgFile="Interface\Tooltips\UI-Tooltip-Background"
                          edgeFile="Interface\Tooltips\UI-Tooltip-Border" tile="true">
            	<EdgeSize>
             		<AbsValue val="16"/>
            	</EdgeSize>
            	<TileSize>
            		<AbsValue val="16"/>
           	</TileSize>
            	<BackgroundInsets>
            		<AbsInset left="5" right="5" top="5" bottom="5"/>
            	</BackgroundInsets>
         	</Backdrop>
	</Frame>
</Ui>

I've tried to convert it to a Lua file which looks like this:

frame = CreateFrame("Frame","ClassBigFrame",UIParent)
frame:SetMovable(true)
frame:SetToplevel(true)

frame:SetBackdrop( {
                bgFile = "Interface\Tooltips\UI-Tooltip-Background",
                edgeFile = "Interface\Tooltips\UI-Tooltip-Border",
                tile = true, tileSize = 16, edgeSize = 16,
                insets = { left = 5, right = 5, top = 5, bottom = 5 }
                } )

frame:SetWidth(100)
frame:SetHeight(100)
frame:SetPoint("CENTER")

frame:Show()

They should both do the same thing, but the XML creates a visible tooltip-like window in the middle of the screen, and the Lua file fails to do that (nothing is visible at all). I know that it is getting processed and the interface thinks its visible since if I add a text string as a child in both cases, I get the text floating in the middle of the screen in the Lua file. So what's the difference between the way these two files are handled?

[Fayen]

Maybe either:

frame:SetHidden(false) or frame:SetVisibility(true)?

[haste]

Frames created by CreateFrame are shown by default.

The symbol \ is used to escape strings.

frame:SetBackdrop( {
                bgFile = "Interface\Tooltips\UI-Tooltip-Background",
                edgeFile = "Interface\Tooltips\UI-Tooltip-Border",
                tile = true, tileSize = 16, edgeSize = 16,
                insets = { left = 5, right = 5, top = 5, bottom = 5 }
                } )

Should be changed into:

frame:SetBackdrop( {
                bgFile = "Interface\\Tooltips\\UI-Tooltip-Background",
                edgeFile = "Interface\\Tooltips\\UI-Tooltip-Border",
                tile = true, tileSize = 16, edgeSize = 16,
                insets = { left = 5, right = 5, top = 5, bottom = 5 }
                } )

you can also use:

frame:SetBackdrop( {
                bgFile = [[Interface\Tooltips\UI-Tooltip-Background]],
                edgeFile = [[Interface\Tooltips\UI-Tooltip-Border]],
                tile = true, tileSize = 16, edgeSize = 16,
                insets = { left = 5, right = 5, top = 5, bottom = 5 }
                } )