varregion: modify MapImageModule structure so it will better merge

with changes made in master.

OpenSim/Region/CoreModules/World/LegacyMap/MapImageModule.cs

@@ -283,6 +283,8 @@ namespace OpenSim.Region.CoreModules.World.LegacyMap
             List<float> z_sortheights = new List<float>();
             List<uint> z_localIDs = new List<uint>();
 
+            try
+            {
                 lock (objs)
                 {
                     foreach (EntityBase obj in objs)
@@ -593,9 +595,15 @@ namespace OpenSim.Region.CoreModules.World.LegacyMap
                             //g.FillRectangle(rectDrawStruct.brush , rectDrawStruct.rect);
                         }
                     }
+                }   // lock(objs)
+            }
+            finally
+            {
+                foreach (DrawStruct ds in z_sort.Values)
+                    ds.brush.Dispose();
+            }
 
             g.Dispose();
-            } // lock entities objs
 
             m_log.Debug("[MAPTILE]: Generating Maptile Step 2: Done in " + (Environment.TickCount - tc) + " ms");
             return mapbmp;