--- gigedit/trunk/src/gigedit/CombineInstrumentsDialog.cpp	2020/05/29 23:25:06	3782
+++ gigedit/trunk/src/gigedit/CombineInstrumentsDialog.cpp	2020/05/30 00:14:27	3783
@@ -412,6 +412,23 @@
 };
 typedef std::vector<CopyAssignSchedEntry> CopyAssignSchedule;
 
+/** @brief Constrain @a dimCase according to @a rgn's dimension zones.
+ *
+ * To avoid @a dimCase being an invalid dimension region selection on @a rgn,
+ * this function automatically wraps (if required) the individual dimension case
+ * entries according to region's actual amount of dimension zones.
+ *
+ * @param dimCase - dimension case to be potentially corrected
+ * @param rgn - the region upon @a dimCase shall be corrected for
+ */
+static void wrapDimCase(DimensionCase& dimCase, gig::Region* rgn) {
+    for (auto& it : dimCase) {
+        gig::dimension_def_t* def = rgn->GetDimensionDefinition(it.first);
+        const int zones = (def) ? def->zones : 1;
+        it.second %= zones;
+    }
+}
+
 /** @brief Schedule copying DimensionRegions from source Region to target Region.
  *
  * Schedules copying the entire articulation informations (including sample
@@ -456,6 +473,13 @@
         uint dstDimValues[8] = {};
         DimensionCase srcDimCase = dimCase;
         DimensionCase dstDimCase = dimCase;
+
+        // source might have less zones than destination, so to prevent output
+        // instrument ending up with NULL samples in some of the dimension
+        // zones, wrap here the source zone according to the amount of zones the
+        // source really has
+        wrapDimCase(srcDimCase, inRgn);
+
         srcDimCase[mainDim] = iSrcMainBit;
         dstDimCase[mainDim] = iDstMainBit;