begin{figure}[htpb]

    \centering

    \begin{minipage}{.49\linewidth}

        \center{\includegraphics[width=1\linewidth]{window_layout1.png}}\\ a)

        %TODO High res image replace

does this mean we still need better png here?

Also, can illustrative pngs be compressed (lossy) with pngquant utility? It makes paletted pngs. Not sure how various pdf viewers will react to that ....