Shoutbox

I've spent several days before I began understand the MPL! script documentation (very bad formated and overall documentation...(compare to AutoIT script documentation) and required knowledge level is way beyond that says in the introduction)
The XML Shema says that <LeftControls> cannot contain <Attributes>
yet, in order to make a button default, it has to have <Attributes> in it:

code:

---

    <DialogTmpl>
        <BottomBar Style="None">
          <LeftControls>
                <Control xsi:type="ButtonControl" Id="btnSave">
                    <Position Top="3" Width="50" Left="0"/>
                    <Caption>Save</Caption>
          <Attributes><IsDefault>true</IsDefault></Attributes>
                </Control>
            </LeftControls>
        </BottomBar>
    </DialogTmpl>

---

It fails validation, but! it actually works...is it because documentation is out of date?

<LeftControls> does not contain <Attributes>, <Control> does...