Summary: Please give players the possibility to resize the size of the minimap or resize the whole panel which contains the minimap (and then let the minimap automatically resize to fill the panel horizontally).
I think it would be a good idea if the minimap (or the entire panel with the map) could be resized. I understand that netbooks want as little space wasted as possible, but when I play on a 20,000 tile map on a bigger screen I would be happy to waste a few additional pixels to have a bigger minimap. I personally prefer to see the whole world, if possible.
Right now, the map is very small in the GTK2 client and even smaller in the GTK3 client (due to the scroll bars). In the GTK3 client the scrollbars alone take a good amount of the space. Also, even when the minimap is detached in the GTK3 client (as a separate window), the map itself does not resize when the window is resized.