Bug 55256 [Colors/Fonts] Rollback change to ColorRegistry for gets() on colors that do not exist
bundles/org.eclipse.jface/src/org/eclipse/jface/resource/ColorRegistry.java
stringToColor.clear();
		staleColors.clear();					
	}
	/* (non-Javadoc)
	 * @see org.eclipse.jface.resource.ResourceRegistry#hasValueFor(java.lang.String)
	 */
	public boolean hasValueFor(String colorKey) {
		return stringToRGB.containsKey(colorKey);
	}
	/**
	 * Hook a dispose listener on the SWT display.
	 */
	private void hookDisplayDispose() {
		display.disposeExec(displayRunnable);
	}
	/**
	 * Adds (or replaces) a color to this color registry under the given 
	 * symbolic name.
	 * <p>
	 * A property change event is reported whenever the mapping from a symbolic
	 * name to a color changes. The source of the event is this registry; the
	 * property name is the symbolic color name.
	 * </p>
	 * 
	 * @param symbolicName the symbolic color name
	 * @param colorData an <code>RGB</code> object
	 */
	public void put(String symbolicName, RGB colorData) {
		put(symbolicName, colorData, true);
	}