Bug 74708 [Encoding] IDEEncodingPreferencePage does not disable OK when invalid encoding is entered
20040921-2000 If you enter an invalid encoding in the IDEEncodingsPreferencePage you will still be able to select OK STEPS 1) Open the Editors preference page 2) Type ffff 3) You are warned but OK is still enabled.
bundles/org.eclipse.ui.ide/src/org/eclipse/ui/internal/ide/dialogs/ResourceInfoPage.java
*         resource is either not a linked resource or it is not using a
	 *         path variable.
	 */
	private boolean isPathVariable(IResource resource) {
		if (!resource.isLinked())
			return false;
		IPath resolvedLocation = resource.getLocation();
		if (resolvedLocation == null) {
			
			return true;
		}
		IPath rawLocation = resource.getRawLocation();
		if (resolvedLocation.equals(rawLocation))
			return false;
		return true;
	}
	/**
	 * Reset the editableBox to the false.
	 */
	protected void performDefaults() {
		
		if (this.editableBox != null)
			this.editableBox.setSelection(false);
		
		if (this.derivedBox != null)
			this.derivedBox.setSelection(false);
		encodingEditor.loadDefault();
		
		
	}