resource leak detection

src/dlangui/core/logger.d

@@ -346,3 +346,6 @@ void onResourceDestroyWhileShutdown(string resourceName, string objname = null)
     Log.e("Resource leak: destroying resource while shutdown! ", resourceName, " ", objname);
 }
 
+/// set to true when exiting main - to detect destructor calls for resources by GC
+__gshared bool APP_IS_SHUTTING_DOWN = false;
+

src/dlangui/graphics/drawbuf.d

@@ -95,6 +95,10 @@ class DrawBuf : RefCountedObject {
     debug private static __gshared int _instanceCount;
     debug @property static int instanceCount() { return _instanceCount; }
     ~this() {
+        /*import core.memory : gc_inFinalizer;*/
+        if (APP_IS_SHUTTING_DOWN/* || gc_inFinalizer*/)
+            onResourceDestroyWhileShutdown("DrawBuf", this.classinfo.name);
+
         debug _instanceCount--;
         clear();
     }

src/dlangui/platforms/common/platform.d

@@ -1605,5 +1605,3 @@ extern(C) void initResourceManagers();
 extern (C) void initSharedResourceManagers();
 
 
-
-

src/dlangui/platforms/console/consoleapp.d

@@ -445,6 +445,7 @@ extern(C) int DLANGUImain(string[] args) {
     releaseResourcesOnAppExit();
 
     Log.d("Exiting main");
+    APP_IS_SHUTTING_DOWN = true;
 
     return result;
 }

src/dlangui/platforms/sdl/sdlapp.d

@@ -1805,6 +1805,7 @@ int sdlmain(string[] args) {
     releaseResourcesOnAppExit();
 
     Log.d("Exiting main");
+    APP_IS_SHUTTING_DOWN = true;
 
     return res;
 }

src/dlangui/platforms/windows/winapp.d

@@ -339,6 +339,11 @@ class Win32Window : Window {
 
     ~this() {
         debug Log.d("Window destructor");
+        if (_drawbuf) {
+            destroy(_drawbuf);
+            _drawbuf = null;
+        }
+            
         /*
         static if (ENABLE_OPENGL) {
             import derelict.opengl3.wgl;
@@ -1262,6 +1267,11 @@ int myWinMain(void* hInstance, void* hPrevInstance, char* lpCmdLine, int iCmdSho
     releaseResourcesOnAppExit();
 
     Log.d("Exiting main");
+    APP_IS_SHUTTING_DOWN = true;
+    import core.memory : GC;
+    Log.d("Calling GC.collect");
+    GC.collect();
+    Log.e("Non-zero DrawBuf instance count when exiting: ", DrawBuf.instanceCount);
 
     return result;
 }