Whoops, that really shouldn't be const.

Source/Atomic/Resource/Image.cpp

@@ -2094,7 +2094,7 @@ Image* Image::GetSubimage(const IntRect& rect) const
     }
 }
 
-bool Image::SetSubimage(const Image* image, const IntRect& rect) const
+bool Image::SetSubimage(const Image* image, const IntRect& rect)
 {
     if (!data_)
         return false;

Source/Atomic/Resource/Image.h

@@ -199,7 +199,7 @@ public:
     /// Return subimage from the image by the defined rect or null if failed. 3D images are not supported. You must free the subimage yourself.
     Image* GetSubimage(const IntRect& rect) const;
     /// Copy contents of the image into the defined rect, scaling if necessary. This image should already be large enough to include the rect. Compressed and 3D images are not supported.
-    bool SetSubimage(const Image* image, const IntRect& rect) const;
+    bool SetSubimage(const Image* image, const IntRect& rect);
     /// Return an SDL surface from the image, or null if failed. Only RGB images are supported. Specify rect to only return partial image. You must free the surface yourself.
     SDL_Surface* GetSDLSurface(const IntRect& rect = IntRect::ZERO) const;
     /// Precalculate the mip levels. Used by asynchronous texture loading.