code: public final boolean selectSRE(ISREInstall sre) {
  		if (sre == null) {
  			if (this.enableSystemWideSelector) {
  				return selectSystemWideSRE();
  			}
  			if (!this.projectProviderFactories.isEmpty()) {
  				return selectProjectSRE();
  			}
  		}
  		return selectSpecificSRE(sre);
  	}
docs: Change the selected SRE. If <code>null</code> is given as parameter,
  and this block enables to select the system-wide SRE, then
  the system-wide SRE is selected. If the block is not enabling the
  system-wide SRE, the specific SRE is reset to the system-wide
  SRE.
  
  @param sre the sre, if <code>null</code> reset to default.
  @return <code>true</code> if the selection changed.
  @see #selectSpecificSRE(ISREInstall)