Fix creating a minimized window in SDL to not cause focus to be stolen (because ShowWindow( hwnd, SW_MINIMIZE ) would be called after creation, thus changing focus to the prior window based on some per-app list in windows, rather than the window being created with WS_MINIMIZED to start with).

This means we have to consider SDL_WINDOW_MINIMIZED a window creation flag, but on non-windows platforms we just remove it and let the normal FinishWindowCreation re-apply and do the minimize as I have no idea what is right on them or if anything should change.

CR: Phil

src/video/SDL_video.c

@@ -1322,7 +1322,7 @@ SDL_UpdateFullscreenMode(SDL_Window * window, SDL_bool fullscreen)
 }
 
 #define CREATE_FLAGS \
-    (SDL_WINDOW_OPENGL | SDL_WINDOW_BORDERLESS | SDL_WINDOW_RESIZABLE | SDL_WINDOW_ALLOW_HIGHDPI | SDL_WINDOW_ALWAYS_ON_TOP | SDL_WINDOW_SKIP_TASKBAR | SDL_WINDOW_POPUP_MENU | SDL_WINDOW_UTILITY | SDL_WINDOW_TOOLTIP | SDL_WINDOW_VULKAN)
+    (SDL_WINDOW_OPENGL | SDL_WINDOW_BORDERLESS | SDL_WINDOW_RESIZABLE | SDL_WINDOW_ALLOW_HIGHDPI | SDL_WINDOW_ALWAYS_ON_TOP | SDL_WINDOW_SKIP_TASKBAR | SDL_WINDOW_POPUP_MENU | SDL_WINDOW_UTILITY | SDL_WINDOW_TOOLTIP | SDL_WINDOW_VULKAN | SDL_WINDOW_MINIMIZED)
 
 static void
 SDL_FinishWindowCreation(SDL_Window *window, Uint32 flags)
@@ -1480,6 +1480,13 @@ SDL_CreateWindow(const char *title, int x, int y, int w, int h, Uint32 flags)
         return NULL;
     }
 
+	// Clear minimized if not on windows, only windows handles it at create rather than FinishWindowCreation,
+	// but it's important or window focus will get broken on windows!
+#if !defined(__WIN32__)
+	if ( window->flags & SDL_WINDOW_MINIMIZED )
+		window->flags &= ~SDL_WINDOW_MINIMIZED;
+#endif
+
 #if __WINRT__ && (NTDDI_VERSION < NTDDI_WIN10)
     /* HACK: WinRT 8.x apps can't choose whether or not they are fullscreen
        or not.  The user can choose this, via OS-provided UI, but this can't

src/video/windows/SDL_windowswindow.c

@@ -97,6 +97,10 @@ GetWindowStyle(SDL_Window * window)
         if (window->flags & SDL_WINDOW_RESIZABLE) {
             style |= STYLE_RESIZABLE;
         }
+
+		/* Need to set initialize minimize style, or when we call ShowWindow with WS_MINIMIZE it will activate a random window */
+		if ( window->flags & SDL_WINDOW_MINIMIZED )
+			style |= WS_MINIMIZE;
     }
     return style;
 }
@@ -335,6 +339,9 @@ WIN_CreateWindow(_THIS, SDL_Window * window)
     /* Inform Windows of the frame change so we can respond to WM_NCCALCSIZE */
     SetWindowPos(hwnd, NULL, 0, 0, 0, 0, SWP_FRAMECHANGED | SWP_NOSIZE | SWP_NOZORDER | SWP_NOMOVE | SWP_NOACTIVATE);
 
+	if ( window->flags & SDL_WINDOW_MINIMIZED )
+		ShowWindow( hwnd, SW_SHOWMINNOACTIVE );
+
     if (!(window->flags & SDL_WINDOW_OPENGL)) {
         return 0;
     }