--- libgig/trunk/src/gig.cpp	2021/06/17 11:41:45	3938
+++ libgig/trunk/src/gig.cpp	2021/06/18 14:56:53	3943
@@ -5394,7 +5394,8 @@
      * @param dst - destination instrument at which this instrument will be
      *              moved to, or pass NULL for moving to end of list
      * @throw gig::Exception if this instrument and target instrument are not
-     *                       part of the same file
+     *                       part of the same file, as well as on unexpected
+     *                       internal error
      */
     void Instrument::MoveTo(Instrument* dst) {
         if (dst && GetParent() != dst->GetParent())
@@ -5411,11 +5412,17 @@
 
             File::InstrumentList::iterator itFrom =
                 std::find(list.begin(), list.end(), static_cast<DLS::Instrument*>(this));
+            if (itFrom == list.end())
+                throw Exception(
+                    "gig::Instrument::MoveTo(): unexpected missing membership "
+                    "of this instrument."
+                );
+            list.erase(itFrom);
 
             File::InstrumentList::iterator itTo =
                 std::find(list.begin(), list.end(), static_cast<DLS::Instrument*>(dst));
 
-            list.splice(itTo, list, itFrom);
+            list.insert(itTo, this);
         }
 
         // move the instrument's actual list RIFF chunk appropriately
@@ -6204,8 +6211,11 @@
      */
     void Group::MoveAll() {
         // get "that" other group first
+        size_t i = 0;
         Group* pOtherGroup = NULL;
-        for (pOtherGroup = pFile->GetFirstGroup(); pOtherGroup; pOtherGroup = pFile->GetNextGroup()) {
+        for (pOtherGroup = pFile->GetGroup(i); pOtherGroup;
+             pOtherGroup = pFile->GetGroup(++i))
+        {
             if (pOtherGroup != this) break;
         }
         if (!pOtherGroup) throw Exception(
@@ -6570,7 +6580,7 @@
      * @param pProgress - optional: callback function for progress notification
      * @returns  sought instrument or NULL if there's no such instrument
      */
-    Instrument* File::GetInstrument(uint index, progress_t* pProgress) {
+    Instrument* File::GetInstrument(size_t index, progress_t* pProgress) {
         if (!pInstruments) {
             // TODO: hack - we simply load ALL samples here, it would have been done in the Region constructor anyway (ATM)
 
@@ -6601,12 +6611,8 @@
             }
         }
         if (!pInstruments) return NULL;
-        InstrumentsIterator = pInstruments->begin();
-        for (uint i = 0; InstrumentsIterator != pInstruments->end(); i++) {
-            if (i == index) return static_cast<gig::Instrument*>( *InstrumentsIterator );
-            InstrumentsIterator++;
-        }
-        return NULL;
+        if (index >= pInstruments->size()) return NULL;
+        return static_cast<gig::Instrument*>( (*pInstruments)[index] );
     }
 
     /** @brief Add a new instrument definition.