Allow to chose/visualize color map as background images

[PhotoComix]

Till M3D supported only 25 maps it was not needed , but with more as now , with many maps is close to the impossible find the right map just remembering its numbers ( actually i have more then 2000 maps .. )

I always solve opening a image viewer to search

If would be possible search the map as when searching BG images( opening a pop out window that show the thumbnails ) will make the  search easier

It is not a big issue but since is already implemented for the background image search maybe same solution may be applied to search the map