Mac: don't ignore mouse clicks on the top pixel of a window (thanks, Joshua!).

Fixes Bugzilla #3190.

src/video/cocoa/SDL_cocoawindow.m

@@ -823,7 +823,14 @@ SetWindowStyle(SDL_Window * window, unsigned int style)
 
     /* Ignore events that aren't inside the client area (i.e. title bar.) */
     if ([theEvent window]) {
-        const NSRect windowRect = [[[theEvent window] contentView] frame];
+        NSRect windowRect = [[[theEvent window] contentView] frame];
+
+        /* add one to size, since NSPointInRect is exclusive of the bottom
+           edges, which mean it misses the top of the window by one pixel
+           (as the origin is the bottom left). */
+        windowRect.size.width += 1;
+        windowRect.size.height += 1;
+
         if (!NSPointInRect([theEvent locationInWindow], windowRect)) {
             return;
         }