Bug 294790 [KeyBindings] LegacyActionTools should support SWT.F13 - F20
bundles/org.eclipse.jface/src/org/eclipse/jface/action/LegacyActionTools.java
* Command) of the key event.
	 * 
	 * @param keyCode
	 *            The key code for which the modifier string is desired.
	 * @return The string representation of the key code; never
	 *         <code>null</code>.
	 */
	private static String getModifierString(int keyCode) {
		String modString = ""; 
		if ((keyCode & SWT.CTRL) != 0) {
			modString = findModifierString(keyCode & SWT.CTRL);
		}
		if ((keyCode & SWT.ALT) != 0) {
			if (modString.equals("")) { 
				modString = findModifierString(keyCode & SWT.ALT);
			} else {
				modString = modString
						+ "+" + findModifierString(keyCode & SWT.ALT); 
			}
		}
		if ((keyCode & SWT.SHIFT) != 0) {
			if (modString.equals("")) { 
				modString = findModifierString(keyCode & SWT.SHIFT);
			} else {
				modString = modString
						+ "+" + findModifierString(keyCode & SWT.SHIFT); 
			}
		}
		if ((keyCode & SWT.COMMAND) != 0) {
			if (modString.equals("")) {