fix(ScrollArea): renderingBoIds concurrency and add immutable view

src/main/java/de/extio/game_engine/menu/OptionsModule.java

@@ -134,7 +134,7 @@ public class OptionsModule extends AbstractClientModule implements OptionsModule
 
 	@Override
 	public void refreshContent() {
-		for (final var boId : this.contentScrollArea.getRenderingBoIds().toArray(new String[0])) {
+		for (final var boId : this.contentScrollArea.getRenderingBoIds()) {
 			this.contentScrollArea.removeRenderingBo(boId);
 		}
 		for (final var tab : this.tabs) {

src/main/java/de/extio/game_engine/menu/ThemeEditorModule.java

@@ -222,7 +222,7 @@ public class ThemeEditorModule extends AbstractClientModule implements OptionsTh
 	
 	private void setupEditor() {
 		this.editorWindow.clearRenderingBos();
-		for (final var boId : this.scrollArea.getRenderingBoIds().toArray(new String[0])) {
+		for (final var boId : this.scrollArea.getRenderingBoIds()) {
 			this.scrollArea.removeRenderingBo(boId);
 		}
 		this.colorSlotByControlId.clear();

src/main/java/de/extio/game_engine/renderer/container/ScrollArea.java

@@ -2,6 +2,7 @@ package de.extio.game_engine.renderer.container;
 
 import java.util.Collections;
 import java.util.HashSet;
+import java.util.List;
 import java.util.Objects;
 import java.util.Set;
 
@@ -41,15 +42,19 @@ public class ScrollArea implements WindowComponent {
 	
 	protected final Set<String> renderingBoIds = Collections.synchronizedSet(new HashSet<>());
 
+	protected volatile Set<String> renderingBoIdsView = null;
+
+	protected volatile boolean renderingBoIdsViewDirty = true;
+	
 	protected final Area2 relativeArea = new Area2(ImmutableCoordI2.zero(), ImmutableCoordI2.one());
 	
-	protected Window parent;
+	protected volatile Window parent;
 	
-	protected double scrollPositionVertical = 1.0; // 1.0 = top, 0.0 = bottom
+	protected volatile double scrollPositionVertical = 1.0; // 1.0 = top, 0.0 = bottom
 	
-	protected double scrollPositionHorizontal = 0.0; // 0.0 = left, 1.0 = right
+	protected volatile double scrollPositionHorizontal = 0.0; // 0.0 = left, 1.0 = right
 	
-	protected int verticalScrollInputRevision = 0;
+	protected volatile int verticalScrollInputRevision = 0;
 	
 	public ScrollArea(final RenderingBoPool renderingBoPool, final EventService eventService) {
 		this.renderingBoPool = renderingBoPool;
@@ -169,6 +174,7 @@ public class ScrollArea implements WindowComponent {
 	
 	public void putRenderingBo(final RenderingBo renderingBo) {
 		this.renderingBoIds.add(renderingBo.getId());
+		this.renderingBoIdsViewDirty = true;
 		this.parent.putRenderingBo(renderingBo);
 	}
 	
@@ -178,6 +184,7 @@ public class ScrollArea implements WindowComponent {
 	
 	public void removeRenderingBo(final String renderingBoId) {
 		this.renderingBoIds.remove(renderingBoId);
+		this.renderingBoIdsViewDirty = true;
 		this.parent.removeRenderingBo(renderingBoId);
 	}
 	
@@ -263,9 +270,21 @@ public class ScrollArea implements WindowComponent {
 		this.relativeArea.setDimension(relativeArea.getDimension().toImmutableCoordI2());
 	}
 	
+	/**
+	 * Returns an immutable copy of the rendering BO IDs currently in this scroll area.
+	 *
+	 * @return an immutable {@link List} containing all rendering BO IDs; safe to iterate
+	 *         while the scroll area is being modified
+	 */
 	@Override
 	public Set<String> getRenderingBoIds() {
-		return this.renderingBoIds;
+		synchronized (this.renderingBoIds) {
+			if (this.renderingBoIdsViewDirty) {
+				this.renderingBoIdsView = Collections.unmodifiableSet(new HashSet<>(this.renderingBoIds));
+				this.renderingBoIdsViewDirty = false;
+			}
+			return this.renderingBoIdsView;
+		}
 	}
 	
 	@Override

src/main/java/de/extio/game_engine/storage/dialog/FileSelectionDialogModule.java

@@ -692,7 +692,7 @@ public class FileSelectionDialogModule extends AbstractClientModule {
 	}
 	
 	private void clearScrollArea() {
-		for (final var boId : this.itemsScrollArea.getRenderingBoIds().toArray(new String[0])) {
+		for (final var boId : this.itemsScrollArea.getRenderingBoIds()) {
 			this.itemsScrollArea.removeRenderingBo(boId);
 		}
 	}

src/main/java/de/extio/game_engine/storage/dialog/FileSelectionMoveDialogModule.java

@@ -357,7 +357,7 @@ public class FileSelectionMoveDialogModule extends AbstractClientModule {
 	}
 
 	private void clearScrollArea() {
-		for (final var boId : this.folderScrollArea.getRenderingBoIds().toArray(new String[0])) {
+		for (final var boId : this.folderScrollArea.getRenderingBoIds()) {
 			this.folderScrollArea.removeRenderingBo(boId);
 		}
 	}