some bullshit to fix potential crash

src/document.cpp

@@ -1,5 +1,6 @@
 #include "document.hpp"
 
+#include <algorithm>
 #include <new>
 #include <utility>
 
@@ -26,6 +27,63 @@ namespace anm2ed
         return it->second;
       return 0;
     }
+
+    void restored_snapshot_sanitize(Document& document)
+    {
+      auto& reference = document.reference;
+      auto& documentAnm2 = document.anm2;
+      auto& selection = document.frames.selection;
+
+      auto animationCount = (int)documentAnm2.animations.items.size();
+      if (animationCount <= 0)
+      {
+        reference = {};
+        selection.clear();
+        document.frameTime = 0.0f;
+        return;
+      }
+
+      if (reference.animationIndex < 0 || reference.animationIndex >= animationCount)
+        reference.animationIndex = std::clamp(reference.animationIndex, 0, animationCount - 1);
+
+      auto item = documentAnm2.item_get(reference.animationIndex, reference.itemType, reference.itemID);
+      if (!item)
+      {
+        reference.itemType = ROOT;
+        reference.itemID = -1;
+        item = documentAnm2.item_get(reference.animationIndex, reference.itemType, reference.itemID);
+      }
+
+      if (!item)
+      {
+        reference.frameIndex = -1;
+        selection.clear();
+        document.frameTime = 0.0f;
+        return;
+      }
+
+      auto frameCount = (int)item->frames.size();
+      for (auto it = selection.begin(); it != selection.end();)
+      {
+        if (*it < 0 || *it >= frameCount)
+          it = selection.erase(it);
+        else
+          ++it;
+      }
+
+      if (frameCount <= 0)
+      {
+        reference.frameIndex = -1;
+        document.frameTime = 0.0f;
+        return;
+      }
+
+      if (reference.frameIndex < 0 || reference.frameIndex >= frameCount)
+        reference.frameIndex = selection.empty() ? std::clamp(reference.frameIndex, 0, frameCount - 1)
+                                                : *selection.begin();
+
+      document.frameTime = item->frame_time_from_index_get(reference.frameIndex);
+    }
   }
 
   Document::Document(Anm2& anm2, const std::filesystem::path& path)
@@ -390,7 +448,8 @@ namespace anm2ed
 
   void Document::undo()
   {
-    snapshots.undo();
+    if (!snapshots.undo()) return;
+    restored_snapshot_sanitize(*this);
     toasts.push(std::vformat(localize.get(TOAST_UNDO), std::make_format_args(message)));
     logger.info(std::vformat(localize.get(TOAST_UNDO, anm2ed::ENGLISH), std::make_format_args(message)));
     change(Document::ALL);
@@ -398,7 +457,8 @@ namespace anm2ed
 
   void Document::redo()
   {
-    snapshots.redo();
+    if (!snapshots.redo()) return;
+    restored_snapshot_sanitize(*this);
     toasts.push(std::vformat(localize.get(TOAST_REDO), std::make_format_args(message)));
     logger.info(std::vformat(localize.get(TOAST_REDO, anm2ed::ENGLISH), std::make_format_args(message)));
     change(Document::ALL);

src/imgui/window/animation_preview.cpp

@@ -1132,10 +1132,24 @@ namespace anm2ed::imgui
               }
             }
 
-            if (isLeftPressed) frame_change_apply({.scaleX = step}, anm2::SUBTRACT);
-            if (isRightPressed) frame_change_apply({.scaleX = step}, anm2::ADD);
-            if (isUpPressed) frame_change_apply({.scaleY = step}, anm2::SUBTRACT);
-            if (isDownPressed) frame_change_apply({.scaleY = step}, anm2::ADD);
+            if (isSelectedNullRect)
+            {
+              if (isLeftPressed)
+                frame_change_apply({.positionX = step * 0.5f, .scaleX = step}, anm2::SUBTRACT);
+              if (isRightPressed)
+                frame_change_apply({.positionX = step * 0.5f, .scaleX = step}, anm2::ADD);
+              if (isUpPressed)
+                frame_change_apply({.positionY = step * 0.5f, .scaleY = step}, anm2::SUBTRACT);
+              if (isDownPressed)
+                frame_change_apply({.positionY = step * 0.5f, .scaleY = step}, anm2::ADD);
+            }
+            else
+            {
+              if (isLeftPressed) frame_change_apply({.scaleX = step}, anm2::SUBTRACT);
+              if (isRightPressed) frame_change_apply({.scaleX = step}, anm2::ADD);
+              if (isUpPressed) frame_change_apply({.scaleY = step}, anm2::SUBTRACT);
+              if (isDownPressed) frame_change_apply({.scaleY = step}, anm2::ADD);
+            }
 
             if (isToolDuring)
             {

src/imgui/window/timeline.cpp

@@ -491,7 +491,6 @@ namespace anm2ed::imgui
           if (!animation) return;
           if (auto item = animation->item_get(reference.itemType, reference.itemID))
           {
-            document.snapshot(localize.get(EDIT_PASTE_FRAMES));
             std::set<int> indices{};
             std::string errorString{};
             int insertIndex = (int)item->frames.size();

src/snapshots.cpp

@@ -53,22 +53,26 @@ namespace anm2ed
     redoStack.clear();
   }
 
-  void Snapshots::undo()
+  bool Snapshots::undo()
   {
     if (auto snapshot = undoStack.pop())
     {
       redoStack.push(current);
       current = *snapshot;
+      return true;
     }
+    return false;
   }
 
-  void Snapshots::redo()
+  bool Snapshots::redo()
   {
     if (auto snapshot = redoStack.pop())
     {
       undoStack.push(current);
       current = *snapshot;
+      return true;
     }
+    return false;
   }
 
   void Snapshots::reset()

src/snapshots.hpp

@@ -63,8 +63,8 @@ namespace anm2ed
 
     Snapshot* get();
     void push(const Snapshot&);
-    void undo();
-    void redo();
+    bool undo();
+    bool redo();
     void reset();
     void apply_limit();
   };