Annotations within GFF files can be imported to Gap5 as annotations (sometimes referred to as tags). The "Import GFF Annotatons" function in the main File menu performs this task. Note that in order for this to work the contigs should not have been edited or complemented since the GFF file was created, otherwise the coordinates in the GFF file will not match.
One caveat to this relates to sequence gaps. By default consensus gaps/padding characters are excluded from the contig consensus sequences when counting GFF sequence coordinates. In some cases we may wish to support annotations in a gapped sequence, so the "GFF coordinates are already padded" checkbox may be used to disable this coordinate de-padding process.