Bug 68011 [java search] "Search the JRE System Libraries" looks like a local preference but behaves as a global one... [search]
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/search/JavaSearchPage.java
fLimitTo[DECLARATIONS].setEnabled(true);
		fLimitTo[IMPLEMENTORS].setEnabled(searchFor == INTERFACE || searchFor == TYPE);
		fLimitTo[REFERENCES].setEnabled(true);			
		fLimitTo[ALL_OCCURRENCES].setEnabled(true);
		fLimitTo[READ_ACCESSES].setEnabled(searchFor == FIELD);
		fLimitTo[WRITE_ACCESSES].setEnabled(searchFor == FIELD);
		
	}
	private String[] getPreviousSearchPatterns() {
		
		int patternCount= fPreviousSearchPatterns.size();
		String [] patterns= new String[patternCount];
		for (int i= 0; i < patternCount; i++)
			patterns[i]= ((SearchPatternData) fPreviousSearchPatterns.get(i)).getPattern();
		return patterns;
	}
	
	private int getSearchFor() {
		for (int i= 0; i < fSearchFor.length; i++) {
			if (fSearchFor[i].getSelection())
				return i;
		}
		Assert.isTrue(false, "shouldNeverHappen"); 
		return -1;
	}
	
	private String getPattern() {
		return fPattern.getText();
	}