Add support for component focus and blur

api/src/main/java/com/bartlomiejpluta/base/api/game/gui/component/BaseComponent.java

@@ -3,4 +3,20 @@ package com.bartlomiejpluta.base.api.game.gui.component;
 import com.bartlomiejpluta.base.api.game.gui.base.BaseWidget;
 
 public abstract class BaseComponent extends BaseWidget implements Component {
+   protected boolean focused;
+
+   @Override
+   public boolean isFocused() {
+      return focused;
+   }
+
+   @Override
+   public void focus() {
+      focused = true;
+   }
+
+   @Override
+   public void blur() {
+      focused = false;
+   }
 }

api/src/main/java/com/bartlomiejpluta/base/api/game/gui/component/BaseContainer.java

@@ -66,6 +66,15 @@ public abstract class BaseContainer extends BaseComponent implements Container {
       return childrenHeight;
    }
 
+   @Override
+   public void blur() {
+      super.blur();
+
+      for (var child : children) {
+         child.blur();
+      }
+   }
+
    @Override
    public void handleKeyEvent(KeyEvent event) {
       for (var child : children) {

api/src/main/java/com/bartlomiejpluta/base/api/game/gui/component/Component.java

@@ -3,4 +3,9 @@ package com.bartlomiejpluta.base.api.game.gui.component;
 import com.bartlomiejpluta.base.api.game.gui.base.Widget;
 
 public interface Component extends Widget {
+   boolean isFocused();
+
+   void focus();
+
+   void blur();
 }

api/src/main/java/com/bartlomiejpluta/base/api/game/gui/window/DefaultWindowManager.java

@@ -58,6 +58,13 @@ public class DefaultWindowManager extends BaseWidget implements WindowManager {
       window.onOpen(this);
    }
 
+   @Override
+   public void closeAll() {
+      for (var window : windows) {
+         close();
+      }
+   }
+
    @Override
    public void close() {
       if (windows.isEmpty()) {

api/src/main/java/com/bartlomiejpluta/base/api/game/gui/window/WindowManager.java

@@ -10,4 +10,10 @@ public interface WindowManager extends Widget {
    void close();
 
    int size();
+
+   default void closeAll() {
+      for (int i = 0; i < size(); ++i) {
+         close();
+      }
+   }
 }

engine/src/main/java/com/bartlomiejpluta/base/engine/ui/model/GLFWInput.java

@@ -46,12 +46,12 @@ public class GLFWInput implements Input {
    }
 
    @Override
-   public void addKeyEventHandler(KeyEventHandler handler) {
+   public void addKeyEventHandler(@NonNull KeyEventHandler handler) {
       keyEventHandlers.addLast(handler);
    }
 
    @Override
-   public void removeKeyEventHandler(KeyEventHandler handler) {
+   public void removeKeyEventHandler(@NonNull KeyEventHandler handler) {
       keyEventHandlers.remove(handler);
    }
 }