hi!
one more version
<action name="nextscene">
add(nextsceneindex, get(scene[get(xml.scene)].index),1);
if(nextsceneindex LT scene.count, loadscene(get(scene[get(nextsceneindex)].name), null, MERGE, BLEND(0.7)); );
</action>
<action name="prevscene">
sub(prevsceneindex, get(scene[get(xml.scene)].index),1);
if(prevsceneindex GT -1, loadscene(get(scene[get(nextsceneindex)].name), null, MERGE, BLEND(0.7)); );
</action>
Using: onclick="nextscene()" or onclcik="prevscene();"
Regards
Andrey