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
}
	
	private boolean isValidSearchPattern() {
		if (getPattern().length() == 0) {
			return false;
		}
		if (fJavaElement != null) {
			return true;
		}
		return SearchPattern.createPattern(getPattern(), getSearchFor(), getLimitTo(), SearchPattern.R_EXACT_MATCH) != null;		
	}
	
	
	/* (non-Javadoc)
	 * @see org.eclipse.jface.dialogs.DialogPage#dispose()
	 */
	public void dispose() {
		writeConfiguration();
		super.dispose();
	}
	private void doPatternModified() {
		if (fInitialData != null && getPattern().equals(fInitialData.getPattern()) && fInitialData.getJavaElement() != null && fInitialData.getSearchFor() == getSearchFor()) {
			fCaseSensitive.setEnabled(false);
			fCaseSensitive.setSelection(true);
			fJavaElement= fInitialData.getJavaElement();
		} else {
			fCaseSensitive.setEnabled(true);
			fCaseSensitive.setSelection(fIsCaseSensitive);
			fJavaElement= null;
		}