Hi,
you can change the file fwgm-shrt-code.php
by replacing:
$lout .= '<div class="createPopup gmbdm-map createPopup-'.$option.'" style="overflow: auto;"><div class="innerdiv" style="border:10px solid #000000; z-index:999999999;position:relative; margin:auto; display:block; height:'.$fgm_glightbox_height.'px; width:'.$fgm_glightbox_width.'px;"><div class="cf-close"></div><iframe height='.$fgm_glightbox_height.'px width='.$fgm_glightbox_width.'px src="'.$map_url.'"></iframe></div></div>';
with:
$fgm_blackbox_height=$fgm_glightbox_height+20;
$lout .= '<div class="createPopup gmbdm-map createPopup-'.$option.'" style="overflow: auto;"><div class="innerdiv" style="border:10px solid #000000; z-index:999999999;position:relative; margin:auto; display:block; height:'.$fgm_blackbox_height.'px; width:'.$fgm_glightbox_width.'px;"><div class="cf-close"></div><iframe height='.$fgm_glightbox_height.'px width='.$fgm_glightbox_width.'px src="'.$map_url.'"></iframe></div></div>';
Best
Sebastian