Added a hint to disable windows message processing in SDL_PumpEvents()

SDL_SetHint( SDL_HINT_WINDOWS_ENABLE_MESSAGELOOP, "0" );

include/SDL_hints.h

@@ -196,6 +196,17 @@ extern "C" {
  */
 #define SDL_HINT_WINDOW_FRAME_USABLE_WHILE_CURSOR_HIDDEN    "SDL_WINDOW_FRAME_USABLE_WHILE_CURSOR_HIDDEN"
 
+/**
+ *  \brief  A variable controlling whether the windows message loop is processed by SDL 
+ *
+ *  This variable can be set to the following values:
+ *    "0"       - The window message loop is not run
+ *    "1"       - The window message loop is processed in SDL_PumpEvents()
+ *
+ *  By default SDL will process the windows message loop
+ */
+#define SDL_HINT_WINDOWS_ENABLE_MESSAGELOOP "SDL_WINDOWS_ENABLE_MESSAGELOOP"
+
 /**
  *  \brief  A variable controlling whether grabbing input grabs the keyboard
  *

src/video/windows/SDL_windowsevents.c

@@ -890,6 +890,7 @@ WIN_PumpEvents(_THIS)
     MSG msg;
     DWORD start_ticks = GetTickCount();
 
+    if (g_WindowsEnableMessageLoop) {
         while (PeekMessage(&msg, NULL, 0, 0, PM_REMOVE)) {
             /* Always translate the message in case it's a non-SDL window (e.g. with Qt integration) */
             TranslateMessage(&msg);
@@ -900,6 +901,7 @@ WIN_PumpEvents(_THIS)
                 break;
             }
         }
+    }
 
     /* Windows loses a shift KEYUP event when you have both pressed at once and let go of one.
        You won't get a KEYUP until both are released, and that keyup will only be for the second

src/video/windows/SDL_windowsvideo.c

@@ -39,8 +39,18 @@ static int WIN_VideoInit(_THIS);
 static void WIN_VideoQuit(_THIS);
 
 /* Hints */
+SDL_bool g_WindowsEnableMessageLoop = SDL_TRUE;
 SDL_bool g_WindowFrameUsableWhileCursorHidden = SDL_TRUE;
 
+static void UpdateWindowsEnableMessageLoop(void *userdata, const char *name, const char *oldValue, const char *newValue)
+{
+    if (newValue && *newValue == '0') {
+        g_WindowsEnableMessageLoop = SDL_FALSE;
+    } else {
+        g_WindowsEnableMessageLoop = SDL_TRUE;
+    }
+}
+
 static void UpdateWindowFrameUsableWhileCursorHidden(void *userdata, const char *name, const char *oldValue, const char *newValue)
 {
     if (newValue && *newValue == '0') {
@@ -178,6 +188,7 @@ WIN_VideoInit(_THIS)
     WIN_InitKeyboard(_this);
     WIN_InitMouse(_this);
 
+    SDL_AddHintCallback(SDL_HINT_WINDOWS_ENABLE_MESSAGELOOP, UpdateWindowsEnableMessageLoop, NULL);
     SDL_AddHintCallback(SDL_HINT_WINDOW_FRAME_USABLE_WHILE_CURSOR_HIDDEN, UpdateWindowFrameUsableWhileCursorHidden, NULL);
 
     return 0;

src/video/windows/SDL_windowsvideo.h

@@ -171,6 +171,7 @@ typedef struct SDL_VideoData
     TSFSink *ime_ippasink;
 } SDL_VideoData;
 
+extern SDL_bool g_WindowsEnableMessageLoop;
 extern SDL_bool g_WindowFrameUsableWhileCursorHidden;
 
 typedef struct IDirect3D9 IDirect3D9;