in editor_basics/src/main/java/org/intellij/sdk/editor/EditorHandlerIllustration.java [52:62]
public void update(@NotNull final AnActionEvent e) {
final Project project = e.getProject();
final Editor editor = e.getData(CommonDataKeys.EDITOR);
// Make sure at least one caret is available
boolean menuAllowed = false;
if (editor != null && project != null) {
// Ensure the list of carets in the editor is not empty
menuAllowed = !editor.getCaretModel().getAllCarets().isEmpty();
}
e.getPresentation().setEnabledAndVisible(menuAllowed);
}