root/galaxy-central/display_applications/ucsc/maf_customtrack.xml

<display id="ucsc_maf_customtrack" version="1.0.0" name="display at UCSC" inherit="True">
    <!-- Load links from file: one line to one link -->
    <dynamic_links from_file="tool-data/shared/ucsc/ucsc_build_sites.txt" skip_startswith="#" id="0" name="0">
        <!-- Define parameters by column from file, allow splitting on builds -->
        <dynamic_param name="site_id" value="0"/>
        <dynamic_param name="ucsc_link" value="1"/>
        <dynamic_param name="builds" value="2" split="True" separator="," />
        <!-- Filter out some of the links based upon matching site_id to a Galaxy application configuration parameter and by dataset dbkey -->
        <filter>${site_id in $APP.config.ucsc_display_sites}</filter>
        <filter>${dataset.dbkey in $builds}</filter>
        <!-- We define url and params as normal, but values defined in dynamic_param are available by specified name -->
        <url>${ucsc_link}db=${qp($maf_customtrack_file.dbkey)}&amp;position=${maf_customtrack_file.metadata.vp_chromosome}:${maf_customtrack_file.metadata.vp_start}-${maf_customtrack_file.metadata.vp_end}&amp;hgt.customText=${maf_customtrack_file.qp}</url>
        <param type="data" name="maf_customtrack_file" url="galaxy_${DATASET_HASH}.maf" format="mafcustomtrack"/>
    </dynamic_links>
</display>