With the overhelming success of the release of JPortal version 1.2 - people started "modding" JPortal - to have it look like something which it is.
Starting with version 1.3 there is limitted theme support.
Here a short list of "features".
a new directory "themes" was added
within this directory there can be several sub directories
per default there is only one directory called "default"
this directory contains all pictures (images) used in the game, like title picture and mana symbols and the like
this directory also contains a file called "Theme.xml", which contains (and in the future even more) additional information
you can build your own directories (themes) by copying the default and giving it another name
you can then replace all pictures with you own pictures (type and size must be the same, there is no ingame calculation provided as yet)
Withing the configuration you can find under "Visual" a
combobox which contains all themes - select the one you would like
and a button called Config Theme, to edit additional theme parameters (for now only three)
The new theme will be active after you save the config and restart the game.