if the elements are done by the xmlmind editor its imo irrirevant if its upper lower or mixed case sensetive. but as far as i know mp dosn't matter if its upper or lower or mixed.
Final point: MediaPortal II will use XAML which I know absolutely nothing about but it 's worth investigating in case out efforts here diverge too much.
<control>
<description>seperator animation</description>
<type>animation</type>
<posX>408</posX>
<posY>200</posY>
<width>444</width>
<height>312</height>
<textures>Animations\Guitar\guitar_0010000.png;Animations\Guitar\guitar_0010001.png;</textures>
<duration>0:0:2.0</duration>
<repeatBehavior>0</repeatBehavior>
<fillBehavior>HoldEnd</fillBehavior>
</control>