Right now expand/collapse menu icon is placed only on menu bottom.
I've found that when you have too many items and work on a small screen, after you expand you are not able to collapse because can not access the icon.
My suggestion is to add same icon on menu top.

I've tried changing

function layout_sidebar_begin() {
$t_collapse_block = is_collapsed( 'sidebar' );
$t_block_css = $t_collapse_block ? 'menu-min' : '';

echo '<div id="sidebar" class="sidebar sidebar-fixed responsive compact ' . $t_block_css . '">';

# change - start 
echo '<div id="sidebar" class="sidebar-toggle sidebar-collapse">';
if( layout_is_rtl() ) {
    $t_block_icon = $t_collapse_block ? 'fa-angle-double-left' : 'fa-angle-double-right';
    echo '<i data-icon2="ace-icon fa fa-angle-double-left" data-icon1="ace-icon fa fa-angle-double-right"
    class="ace-icon fa ' . $t_block_icon . '"></i>';
} else {
    $t_block_icon = $t_collapse_block ? 'fa-angle-double-right' : 'fa-angle-double-left';
    echo '<i data-icon2="ace-icon fa fa-angle-double-right" data-icon1="ace-icon fa fa-angle-double-left"
    class="ace-icon fa ' . $t_block_icon . '"></i>';
}
echo '</div>';
# change  - stop 

echo '<ul class="nav nav-list">';

}