Ensures that there's no loading threads while cleaning

Should be changed, as the feeling is less good, memory consumption could get huge, and unuseful threads may continue instead of being stopped.

PBMap.pb

@@ -1059,7 +1059,7 @@ Module PBMap
     ; If MemoryCache is not being used by a download thread
     If PBMap\MemoryCacheAccessNB = 0    
       PBMap\MemoryCacheAccessNB = -1 ; Not really useful as the download thread are now blocked by the mutex, and this procedure is synchronous
-      UnlockMutex(PBMap\MemoryCacheAccessNBMutex)
+      ;UnlockMutex(PBMap\MemoryCacheAccessNBMutex)
       ; If cache size exceeds limit, try to delete the oldest tiles used (first in the time stack)
       Protected CacheSize = MapSize(PBMap\MemCache\Images()) * Pow(PBMap\TileSize, 2) * 4 ; Size of a tile = TileSize * TileSize * 4 bytes (RGBA) 
       Protected CacheLimit = PBMap\Options\MaxMemCache * 1024
@@ -1099,7 +1099,7 @@ Module PBMap
         EndIf
       EndIf
       ; We're no more accessing MemoryCache
-      LockMutex(PBMap\MemoryCacheAccessNBMutex)
+      ;LockMutex(PBMap\MemoryCacheAccessNBMutex)
       PBMap\MemoryCacheAccessNB = 0  ; Not really useful as the download thread are now blocked
     EndIf
     UnlockMutex(PBMap\MemoryCacheAccessNBMutex)
@@ -1287,7 +1287,7 @@ Module PBMap
       *timg\nImage = GetTileFromHDD(CacheFile.s)
       If *timg\nImage
         ; Image found and loaded from HDD
-        *timg\Alpha = 256
+        *timg\Alpha = 0
         *timg\Tile = -1
         ProcedureReturn *timg
       EndIf
@@ -2894,8 +2894,8 @@ CompilerIf #PB_Compiler_IsMainFile
 CompilerEndIf
 
 ; IDE Options = PureBasic 5.60 (Windows - x64)
-; CursorPosition = 2751
+; CursorPosition = 2510
-; FirstLine = 2738
+; FirstLine = 2503
 ; Folding = -------------------
 ; EnableThread
 ; EnableXP