Bug 94399 [preferences] Multiple requests for rebuild
Build: I20050509-2010 1) Open a new workspace 2) Create a Java project 3) Modify at least one preference on every "Compiler" preference page. 4) Click ok -> You are prompted to do a full rebuild for each page that has changed. If you changed three pages, you get three prompt dialogs. The user should only be prompted once. Even worse, all three or four builds are queued up and run one after the other. If you don't cancel the builds, the workspace is rebuilt several times.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/util/CoreUtility.java
public boolean belongsTo(Object family) {
				return ResourcesPlugin.FAMILY_MANUAL_BUILD == family;
			}
		};
		
		buildJob.setRule(ResourcesPlugin.getWorkspace().getRuleFactory().buildRule());
		buildJob.setUser(true);
		return buildJob;
	}
	
	/**
     * Set the autobuild to the value of the parameter and
     * return the old one.
     * 
     * @param state the value to be set for autobuilding.
     * @return the old value of the autobuild state
     */
    public static boolean enableAutoBuild(boolean state) throws CoreException {
        IWorkspace workspace= ResourcesPlugin.getWorkspace();
        IWorkspaceDescription desc= workspace.getDescription();
        boolean isAutoBuilding= desc.isAutoBuilding();
        if (isAutoBuilding != state) {
            desc.setAutoBuilding(state);
            workspace.setDescription(desc);
        }
        return isAutoBuilding;
    }
	
}