Fix subpanel SyncHandlers being cleared if the screen is just being replaced. (#153)

* Fix subpanel SyncHandlers being cleared when the screen is just being replaced

* Move screen capture to the existing `GuiOpenEvent` even in `ClientScreenHandler`

Author: Zorbatron

src/main/java/com/cleanroommc/modularui/screen/ClientScreenHandler.java

@@ -78,21 +78,26 @@ public class ClientScreenHandler {
     private static long ticks = 0L;
 
     private static IMuiScreen lastMui;
+    
+    public static boolean guiIsClosing;
 
     // we need to know the actual gui and not some fake bs some other mod overwrites
     @SubscribeEvent(priority = EventPriority.LOWEST)
     public static void onGuiOpen(GuiOpenEvent event) {
+        GuiScreen newGui = event.getGui();
+        guiIsClosing = newGui == null;
+        
         defaultContext.reset();
-        if (lastMui != null && event.getGui() == null) {
+        if (lastMui != null && newGui == null) {
             if (lastMui.getScreen().getPanelManager().isOpen()) {
                 lastMui.getScreen().getPanelManager().closeAll();
             }
             lastMui.getScreen().getPanelManager().dispose();
             lastMui = null;
-        } else if (event.getGui() instanceof IMuiScreen screenWrapper) {
+        } else if (newGui instanceof IMuiScreen screenWrapper) {
             if (lastMui == null) {
                 lastMui = screenWrapper;
-            } else if (lastMui == event.getGui()) {
+            } else if (lastMui == newGui) {
                 lastMui.getScreen().getPanelManager().reopen();
             } else {
                 if (lastMui.getScreen().getPanelManager().isOpen()) {
@@ -103,7 +108,7 @@ public static void onGuiOpen(GuiOpenEvent event) {
             }
         }
 
-        if (event.getGui() instanceof IMuiScreen muiScreen) {
+        if (newGui instanceof IMuiScreen muiScreen) {
             Objects.requireNonNull(muiScreen.getScreen(), "ModularScreen must not be null!");
             if (currentScreen != muiScreen.getScreen()) {
                 if (hasScreen()) {
@@ -114,7 +119,7 @@ public static void onGuiOpen(GuiOpenEvent event) {
                 currentScreen = muiScreen.getScreen();
                 fpsCounter.reset();
             }
-        } else if (hasScreen() && getMCScreen() != null && event.getGui() != getMCScreen()) {
+        } else if (hasScreen() && getMCScreen() != null && newGui != getMCScreen()) {
             currentScreen.onCloseParent();
             currentScreen = null;
             lastChar = null;

src/main/java/com/cleanroommc/modularui/value/sync/ModularSyncManager.java

@@ -1,6 +1,7 @@
 package com.cleanroommc.modularui.value.sync;
 
 import com.cleanroommc.modularui.ModularUI;
+import com.cleanroommc.modularui.screen.ClientScreenHandler;
 import com.cleanroommc.modularui.screen.ModularContainer;
 import com.cleanroommc.modularui.widgets.slot.SlotGroup;
 import com.cleanroommc.bogosorter.api.ISortingContextBuilder;
@@ -61,7 +62,9 @@ public void detectAndSendChanges(boolean init) {
     }
 
     public void onClose() {
-        this.panelSyncManagerMap.values().forEach(PanelSyncManager::onClose);
+        if (ClientScreenHandler.guiIsClosing) {
+            this.panelSyncManagerMap.values().forEach(PanelSyncManager::onClose);
+        }
     }
 
     public void onOpen() {