A graphical interfaces editor. The Crow Designer is a visual editor for building graphical user interfaces. Interfaces are saved in files of the GuiXml format and may be involved in applications by means of the GuiLoader library. During editing, the following instruments are available to a user: a palette of GUI controls, an object tree, an editor canvas and a hierarchical property explorer. The property explorer gives a possibility to work with nested objects and arrays as well as with several selected objects simultaneously. The designer uses \"widgets\" of the GTK+ library as a GUI control kit.