--- libgig/trunk/src/gig.cpp	2019/12/14 17:04:28	3656
+++ libgig/trunk/src/gig.cpp	2020/01/10 11:21:59	3709
@@ -3412,7 +3412,7 @@
         }
 
         File* pFile = (File*) GetParent()->GetParent();
-        bool versiongt2 = pFile->pVersion && pFile->pVersion->major > 2;
+        const bool versiongt2 = pFile->pVersion && pFile->pVersion->major > 2;
         const int iMaxDimensions =  versiongt2 ? 8 : 5;
         const int iMaxDimensionRegions = versiongt2 ? 256 : 32;
 
@@ -3459,6 +3459,32 @@
             }
             store32(&pData[iWavePoolOffset + i * 4], iWaveIndex);
         }
+
+        if (versiongt2) {
+            // add 3dnm list which always seems to be empty
+            RIFF::List* _3dnm = pCkRegion->GetSubList(LIST_TYPE_3DNM);
+            if (!_3dnm) _3dnm = pCkRegion->AddSubList(LIST_TYPE_3DNM);
+
+            // add 3ddp chunk which always seems to have 16 bytes of 0xFF
+            RIFF::Chunk* _3ddp = pCkRegion->GetSubChunk(CHUNK_ID_3DDP);
+            if (!_3ddp) _3ddp =  pCkRegion->AddSubChunk(CHUNK_ID_3DDP, 16);
+            uint8_t* pData = (uint8_t*) _3ddp->LoadChunkData();
+            for (int i = 0; i < 16; i += 4) {
+                store32(&pData[i], 0xFFFFFFFF);
+            }
+
+            // move 3dnm and 3ddp to the end of the region list
+            pCkRegion->MoveSubChunk(pCkRegion->GetSubList(LIST_TYPE_3DNM), (RIFF::Chunk*)NULL);
+            pCkRegion->MoveSubChunk(pCkRegion->GetSubChunk(CHUNK_ID_3DDP), (RIFF::Chunk*)NULL);
+        } else {
+            // this is intended for the user switching from GSt >= 3 version
+            // back to an older format version, delete GSt3 chunks ...
+            RIFF::List* _3dnm = pCkRegion->GetSubList(LIST_TYPE_3DNM);
+            if (_3dnm) pCkRegion->DeleteSubChunk(_3dnm);
+
+            RIFF::Chunk* _3ddp = pCkRegion->GetSubChunk(CHUNK_ID_3DDP);
+            if (_3ddp) pCkRegion->DeleteSubChunk(_3ddp);
+        }
     }
 
     void Region::LoadDimensionRegions(RIFF::List* rgn) {
@@ -3997,9 +4023,23 @@
         // now tempRegion's dimensions and DimensionRegions basically reflect
         // what we wanted to get for this actual Region here, so we now just
         // delete and recreate the dimension in question with the new amount
-        // zones and then copy back from tempRegion       
-        DeleteDimension(oldDef);
-        AddDimension(&newDef);
+        // zones and then copy back from tempRegion. we're actually deleting and
+        // recreating all dimensions here, to avoid altering the precise order
+        // of the dimensions (which would not be an error per so, but it would
+        // cause usability issues with instrument editors)
+        {
+            std::vector<dimension_def_t> oldDefs;
+            for (int i = 0; i < Dimensions; ++i)
+                oldDefs.push_back(pDimensionDefinitions[i]); // copy, don't reference
+            for (int i = Dimensions - 1; i >= 0; --i)
+                DeleteDimension(&pDimensionDefinitions[i]);
+            for (int i = 0; i < oldDefs.size(); ++i) {
+                dimension_def_t& def = oldDefs[i];
+                AddDimension(
+                    (def.dimension == newDef.dimension) ? &newDef : &def
+                );
+            }
+        }
         for (int iSrc = 0; iSrc < 256; ++iSrc) {
             DimensionRegion* srcDimRgn = tempRgn->pDimensionRegions[iSrc];
             if (!srcDimRgn) continue;