Tcl/Tk is the best for me to write scripts and GUI applications, but the ttk::theme concept has a big bug. It uses his own colors without looking for the GUI environments. The 'old' Tk uses the Xresources, so the user can manipulate the Gui on this way. But it seems Ttk doesn't do that (at least on Linux). To get a uniform GUI, tk and ttk share their colors.
The nicest theme looks ugly, if it doesn't match the system environment.
Theme clam on my dark desktop:
xtk::theme provides two themes: 'gtk2' and 'tk'. The color structure follows the concept of gtk and privides five color pairs (back/fore) plus a dark/light pair for each widget type. Widget types are ...
The 'gtk2' theme tries to read the current gtk theme and reads it's configuration. It reads only the default style of gtk. As fallback it uses a builtin config file. So Tk reads the system/x11 colors, the theme 'tk' uses that colors.
If xfce or gnome is detected as DESKTOP_SESSION, 'gtk2' will be set as the default theme, otherwise it uses 'tk' as default.
It is recommended to change the themes with the command ::xtk::theme::ttk::init <Themes>, instead of using the ttk::style theme use <Theme> command.
package require defColor ?0.3?
package require xtk::theme ?0.2?