Ok new to MDX but still expierenced @window embedding?

dialog R {
title "R"
size -1 -1 188 104
option dbu
edit "", 1, 1 5 184 35, multi
button "", 2, 72 63 37 12
}

on *:dialog:R:init:0: {
dll $mdx SetMircVersion $version
dll $mdx MarkDialog $dname
window -ah @preview
did -a $dname 2 grab $window(@preview).hwnd @preview
}

i no im missing sumtin sumwhere
but ther were no tutorials for it or anything to explain it besided the MDX help which doesnt do that much on this can ya help me?