Configuration

wpgtk loads it's configuration from $HOME/.config/wpg/wpg.conf this are the default values the keywords section is explained here.

[settings]
set_wallpaper = true # set wallpaper or not in each color-scheme change
gtk = true           # live reload GTK+ or not
active = 0           # color to use as "active" and "inactive" shades
light_theme = false  # whether to use a light theme or not
editor = gvim        # editor to use on templates
execute_cmd = false  # execute command after applying theme
command = urxvt -e echo hi # command to execute 
backend = wal        # colorscheme generation backend
alpha = 100          # transparency value
smart_sort = true    # sort color-schemes according to xterm standard
auto_adjust = false  # auto-adjust color-schemes when adding them

[keywords]
# custom-key = value

To adjust your settings you can either edit the file directly or use the Options tab in wpg GUI mode, an advantage to doing this is that you can change the settings without actually saving theme for a one-time configuration.