Index: edit.c
==================================================================
--- edit.c
+++ edit.c
@@ -529,10 +529,11 @@
     }
   }
   generation_number_inc=0;
   n=objalloc(m->class);
   if(n==VOIDLINK) return;
+  level_changed=1;
   objects[n]->x=x;
   objects[n]->y=y;
   objects[n]->image=m->img;
   objects[n]->dir=m->dir;
   objects[n]->misc1=m->misc1;
@@ -574,10 +575,11 @@
     case 're': // Resize and clear
       if(argc<3) return 0;
       x=sqlite3_column_int(args,1);
       y=sqlite3_column_int(args,2);
       if(x<1 || y<1 || x>64 || y>64) return 0;
+      level_changed=1;
       annihilate();
       pfwidth=x;
       pfheight=y;
       return 0;
     default:

Index: function.c
==================================================================
--- function.c
+++ function.c
@@ -931,10 +931,11 @@
     if(objects[id]->misc2.t&~3) objects[id]->misc2=NVALUE(0);
     objects[id]->misc3.u=sqlite3_value_int64(argv[6])&0xFFFF;
     objects[id]->misc3.t=sqlite3_value_int64(argv[6])>>32;
     if(objects[id]->misc3.t&~3) objects[id]->misc3=NVALUE(0);
   }
+  level_changed=1;
   return SQLITE_OK;
 }
 
 Module(vt_objects,
   .xBestIndex=vt1_objects_index,

Index: heromesh.h
==================================================================
--- heromesh.h
+++ heromesh.h
@@ -47,10 +47,11 @@
 extern Uint8 message_trace[0x4100/8];
 extern Uint16 level_id,level_ord,level_version,level_code;
 extern unsigned char*level_title;
 extern Uint16*level_index;
 extern int level_nindex;
+extern char level_changed; // 1 if solution is potentially invalidated by edits
 
 #ifdef __GNUC__
 extern char stack_protect_mode;
 extern void*stack_protect_mark;
 extern void*stack_protect_low;

Index: main.c
==================================================================
--- main.c
+++ main.c
@@ -45,10 +45,11 @@
 Uint8 message_trace[0x4100/8];
 Uint16 level_id,level_ord,level_version,level_code;
 unsigned char*level_title;
 Uint16*level_index;
 int level_nindex;
+char level_changed;
 
 #ifdef __GNUC__
 char stack_protect_mode=0;
 void*stack_protect_mark;
 void*stack_protect_low;
@@ -225,10 +226,11 @@
     p=buf=read_lump(FIL_LEVEL,lvl,&sz);
     end=buf+sz;
   }
   if(lvl<0) return "Invalid level ID";
   if(!buf) return "Cannot find level";
+  level_changed=1;
   free(level_title);
   level_title=0;
   annihilate();
   generation_number=TY_MAXTYPE+1;
   generation_number_inc=0;
@@ -349,10 +351,11 @@
     for(i=0;i<level_nindex;i++) if(level_index[i]==lvl) {
       level_ord=i+1;
       break;
     }
   }
+  level_changed=0;
   return 0;
 bad1:
   free(buf);
   return "Corrupted level data";
 bad2: