gitk: add theme selection to color configuration page

gitk allows configuring a particular theme in its configuration file
(default on linux: ~/.config/git/gitk), but offers no ability to modify
this from gitk's configuration editor. Let's add this to the color
configuration page.

Present the offered themes in a list, and allow choosing / modifying a
theme definition file ($themeloader). Update the list of themes if the
theme file is modified, and update the theme if specifically requested
(by default, just change the value for use after gitk is restarted).

Any theme definition file can change the global options database,
affecting potentially any theme. So, the ultimate configuration should
have either
- no theme definition file (themeloader = {}), and a native Tk, theme,
or
- themeloader naming a valid file, and $theme naming a theme defined by
  that file.

But, there is no trivial way to enforce the above. Shrug.

Helped-by: Johannes Sixt <j6t@kdbg.org>
Signed-off-by: Mark Levedahl <mlevedahl@gmail.com>

0 files changed, 0 insertions, 0 deletions