The authors propose a method for learning how to propose informative regions to be labelled for matting. The model is based on an RNN that uses a matting solver as a black box. Given that in principle the matting solver is non-differentiable, the authors rely on posing the training process as a reinforcement learning problem. The problem is interesting, and the overall idea of making the model learn to propose informative regions is nice. However the execution of the idea is unsatisfactory for the following reasons: The reinforcement learning approach described is based on the direct application of the algorithm developed in ref [3] in the paper.