Required components default fallback

[2387skju]

Reset the required components to default, if not found.
After uninstall a component, a fallback is need: will fix #324
(( Required components are: dock, filemanager, panel, window manager. ))

---

Changes in file mate-session/main.c :
Reset will be done, in this case:

• the executable was not found
• and the current value is not empty
  • => this still allows the user to disable a component manual (= by set empty value)
• and the default value is not empty

---

Additional just for the Windowmanager:
Changes in file data/mate-wm :

• checks if the value from gsettings is usable (command) ,
• otherwise just ignore that value and continue the script normal (= will search for another window manager)

(both shortly tested with older Mate Version 1.26 on Debian 13. ; I'm new in C-Language)

[vkareh]

There are some memory management issues, but this is moving in the right direction, thanks.

[2387skju]

Thank you for helping me :-)

Changes:

• variable name swapped each other:
  • g_settings_default_default <=> default_default_provider
  • This is more consistant to the origin code (the lines before).
• replaced: strcmp(.., "") => IS_STRING_EMPTY:
  • Now use of MARCO (( #define IS_STRING_EMPTY(x) ((x)==NULL||(x)[0]=='\0') ))
  • That MACRO is already used a few lines before.
  • I think this is bedder to read and faster. (( other alternative: strlen(str) == 0 )).
• replaced: g_variant_get => g_variant_get_string
  • I think this look a little bit bedder.
  • This is like &s version of g_variant_get_string.

---

I've also tested / think about split the code in a new function:

I'm not sure about it. Just an Idea. In this structure:

append_required_apps()
{
  for  // for each required_components
  {
    append_required_apps_add_component(..., FALSE);
  }
}

append_required_apps_add_component (...,  gboolean is_recursiv_call)
{

  [...] // do add component
  
  if  // if failed && !is_recursiv_call
  {
    // do reset
    ...
    append_required_apps_add_component (..., TRUE);
  }
}

Implemented in Code:

• This branch or commit
• Alternative Version: Has an extra refactor commit: branch or commit