  We used data from the HST UV Legacy Survey of Galactic Globular Clusters to
select the Blue Straggler Star (BSS) population in four intermediate/high
density systems (namely NGC 2808, NGC 6388, NGC 6541 and NGC 7078) through a
"UV-guided search". This procedure consists in using the F275W images in each
cluster to construct the master list of detected sources, and then force it to
the images acquired in the other filters. Such an approach optimizes the
detection of relatively hot stars and allows the detection of complete sample
of BSSs even in the central region of high-density clusters, because the light
from the bright cool giants, which dominates the optical emission in old
stellar systems, is sensibly reduced at UV wavelengths. Our UV-guided
selections of BSSs have been compared to the samples obtained in previous,
optical-driven surveys, clearly demonstrating the efficiency of the UV
approach. In each cluster we also measured the parameter A+, defined as the
area enclosed between the cumulative radial distribution of BSSs and that of a
reference population, which traces the level of BSS central segregation and the
level of dynamical evolution suffered by the system. The values measured for
the four clusters studied in this paper nicely fall along the dynamical
sequence recently presented for a sample of 25 clusters.
