Reply To cazfi
The simplest way to do this would be to just add another set of flag pngs for the tileset to use - the one shown in diplomacy dialog, and which we then make a much higher resolution one compared to normal flag.
I've now started with a different approach - if the feature is enabled (requires .svg support from the client, and user choice even then), we'll use .svg flags and scale those.
Working on the flag svgs it's started annoy me a bit that we have some quite highly detailed flags, but that is completely wasted in that we shrink them to some tiny pngs and ever only show those couple of pixels. One place where we could show a bigger flag image would be the diplomacy dialog.
The simplest way to do this would be to just add another set of flag pngs for the tileset to use - the one shown in diplomacy dialog, and which we then make a much higher resolution one compared to normal flag. However, the simplistic implementation would be a bit wasteful of memory (if that really matter these days) in that those high resolution images would be in memory for all the nations (over 500 of them) even if only a couple of them are in the current game.
As part of #43200, this has also been posted to http://forum.freeciv.org/f/viewtopic.php?f=14&t=92031