  The mass reinserted by young stars of an emerging massive compact cluster
shows a bimodal hydrodynamic behaviour. In the inner part of the cluster, it is
thermally unstable, while in its outer parts it forms an out-blowing wind. The
chemical homogeneity/inhomogeneity of low/high mass clusters demonstrates the
relevance of this solution to the presence of single/multiple stellar
populations. We show the consequences that the thermal instability of the
reinserted mass has to the galactic super-winds.
