Fixed bug 1682 - Resize collapses window instantly to a size of 0 x 124.

Marco Schmidt

After sizing my main window (the only window in my application) through
grabbing the window border with the mouse the window collapses instantly to a
size of 0 x 124. In my application I can not resize the window to a normal size
again.

I tried to reproduce the problem - and here a the minimal steps I found.

I'm running WIN8 x64, VS2012Pro, HG SDL-2.0 tip, WIN32-Build.

Minimal steps to reproduce my problem:

- open solution SDL_VS2012
- make testdraw2 the start project
- pass command line option --resize to the debuggee testdraw2
- starting the application testdraw2
- try to resize the window
- the application window resizes to a minimal size 0 x 124.
- the application crashes to divide by zero .... (this is only the aftermath
but a unhandled error condition)

src/video/windows/SDL_windowsevents.c

@@ -469,8 +469,10 @@ WIN_WindowProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
                size so we don't need to call AdjustWindowRectEx twice */
             min_w -= w;
             min_h -= h;
-            max_w -= w;
-            max_h -= h;
+            if (max_w && max_h) {
+                max_w -= w;
+                max_h -= h;
+            }
 
             size.top = 0;
             size.left = 0;