page in top pages subpages in sidebar

Hello,

I’m trying to have main pages show up in the Blix horizontal page menu while not displaying subpages there ( you can see those in the sidebar)

in header.php i’ve been testing stuff out here, trying to set a condition to not display sub pages –

else {
(is_page($page_id))?$selected = ‘ class=”selected”‘:$selected=”;
echo “<li”.$selected.”>$page_title\n”;
}

becomes something like

else {
if($page_id->post_parent == 0) {
(is_page($page_id))?$selected = ‘ class=”selected”‘:$selected=”;
echo “<li”.$selected.”>$page_title\n”;
}

but this doesn’t work. i’m trying to write code to say display only if parent is the default value otherwise don’t display.

any help would be great.
thanks.