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GUI extensions

weigl, 2019

GUI Extensions defines a couple of extension points for the KeY User Interface. It allows to add new functionality into the gui, without digging through the old UI code. It also should make the UI more consistent, decoupling dependencies and easier to implement new functionality.

General extension points

An extension is defined by an interface, which should be implemented by the new functionality. This interface defines the methods needed to be successfully injected into the UI. GUI Extensions are loaded and found via the ServiceLoader facility of Java. Therefore, you should mention your extension in the appropiate serivce file under META-INF/services/<full-interface-name>. For example, the exploration extension specifies the fully qualified class name org.key_project.exploration.ExplorationExtension in keyext.exploration/src/main/resources/META-INF/services/de.uka.ilkd.key.gui.extension.api.KeYGuiExtension.

Every gui extension should be marked with KeYGuiExtension and is only loaded once. It does not matter on how many extension points it participate.

Different GUI extension should not depend on each other, as Gui Extension should loaded independent.

Basic Extension Metadata

Additional meta data can plugged to an extension by adding the Java annotation @KeYGuiExtension.Info.

Currently: name, description, disabled, optional, priority.

Annotation because of accessible via the class w/o instantiation.

  • Extension Points are now in KeYGuiExtension

General UI facilities

Icon Management

KeYIconManagement and KeYIcon introduces a way of icon management and configuration via UIManager.

Key-stroke Management

KeyStrokeManager reworked. It is now possible to define KeyStrokes in a properties file.

Color Management

Sharing Services accross UI extensions

Brings Lookup a successor for a flexible mediator replacement based on a service architecture, incl. Dependency Injection


Entry point for KeY startup. For hooking into the shutdown handler, register a GUIListener at the KeYMediator.



Use this extension point to add items to context menus. Extend ContextMenuAdapter and override the methods of the menus you wish to extend. It is possible to extend the context menu of the proof list, the proof tree, the taclet info screen and the sequent view.


Implement this interface to add a panel to the UI. It is added to the panel in the left bottom corner.


Implement this interface to add new elements to the main toolbar above the sequent view. Sample code:

private JToolBar extensionToolbar = null;

public JToolBar getToolbar(MainWindow mainWindow) {
    if (extensionToolbar == null) {
        extensionToolbar = new JToolBar();
        extensionToolbar.add(new FooAction(mainWindow, this));
        extensionToolbar.add(new BarAction(mainWindow, this));
    return extensionToolbar;


  • A common settings dialog should replace all existing setting dialogs.
  • A component can register a SettingsProvider to the SettingsManager.getInstance() to participate in the default instance.
  • A SettingsProvider offers mainly a description, a panel, and a handler to save the settings.
  • A SettingsProvider can have children (SettingsProvider).
  • An extension can announce a SettingsProvider by declaring to be KeYGuiExtension.Settings.
  • Existing settings were adopted.

Changes to settings: It is now possible to hook into the proof-independent/-dependent settings by calling addSettings(Settings).



This interface allows you to extend the tooltip displayed when hovering on a term in the sequent view.