[gedit] PreferencesDialog: improvements to color scheme management

[Sébastien Wilmet <swilmet src gnome org>]

commit 94c3b70cbe23e1a8ff61fbc50bc927f1c093fe34
Author: Sébastien Wilmet <swilmet gnome org>
Date:   Thu Apr 23 16:14:39 2020 +0200

    PreferencesDialog: improvements to color scheme management
    
    - The default style scheme is now 'tango', not 'classic'.
    - Make the code more robust in case no style scheme is selected or no
    style scheme is installed.
    
    This commit fixes some critical messages when using the feature to
    add/remove color schemes from the GUI. This feature is still a bit
    broken, it will be fixed by a later commit (to correctly update the
    state when a style scheme is installed/uninstalled).

 gedit/gedit-preferences-dialog.c | 34 +++++++++++++++++++++-------------
 1 file changed, 21 insertions(+), 13 deletions(-)
---
diff --git a/gedit/gedit-preferences-dialog.c b/gedit/gedit-preferences-dialog.c
index dd626f869..81a3db809 100644
--- a/gedit/gedit-preferences-dialog.c
+++ b/gedit/gedit-preferences-dialog.c
@@ -497,12 +497,16 @@ style_scheme_changed (GtkSourceStyleSchemeChooser *chooser,
                       GeditPreferencesDialog      *dlg)
 {
        GtkSourceStyleScheme *scheme;
-       const gchar *id;
 
        scheme = gtk_source_style_scheme_chooser_get_style_scheme (chooser);
-       id = gtk_source_style_scheme_get_id (scheme);
+       if (scheme != NULL)
+       {
+               const gchar *id;
+
+               id = gtk_source_style_scheme_get_id (scheme);
+               g_settings_set_string (dlg->editor, GEDIT_SETTINGS_SCHEME, id);
+       }
 
-       g_settings_set_string (dlg->editor, GEDIT_SETTINGS_SCHEME, id);
        set_buttons_sensisitivity_according_to_scheme (dlg, scheme);
 }
 
@@ -515,18 +519,14 @@ get_default_color_scheme (GeditPreferencesDialog *dlg)
 
        manager = gtk_source_style_scheme_manager_get_default ();
 
-       pref_id = g_settings_get_string (dlg->editor,
-                                        GEDIT_SETTINGS_SCHEME);
-
-       scheme = gtk_source_style_scheme_manager_get_scheme (manager,
-                                                            pref_id);
+       pref_id = g_settings_get_string (dlg->editor, GEDIT_SETTINGS_SCHEME);
+       scheme = gtk_source_style_scheme_manager_get_scheme (manager, pref_id);
        g_free (pref_id);
 
        if (scheme == NULL)
        {
-               /* Fall-back to classic style scheme */
-               scheme = gtk_source_style_scheme_manager_get_scheme (manager,
-                                                                    "classic");
+               /* Fall-back to tango style scheme */
+               scheme = gtk_source_style_scheme_manager_get_scheme (manager, "tango");
        }
 
        return scheme;
@@ -842,6 +842,11 @@ uninstall_scheme_clicked (GtkButton              *button,
 
        scheme = gtk_source_style_scheme_chooser_get_style_scheme (GTK_SOURCE_STYLE_SCHEME_CHOOSER 
(dlg->schemes_list));
 
+       if (scheme == NULL)
+       {
+               return;
+       }
+
        if (!uninstall_style_scheme (scheme))
        {
                tepl_utils_show_warning_dialog (GTK_WINDOW (dlg),
@@ -880,8 +885,11 @@ setup_font_colors_page_style_scheme_section (GeditPreferencesDialog *dlg)
                          G_CALLBACK (uninstall_scheme_clicked),
                          dlg);
 
-       gtk_source_style_scheme_chooser_set_style_scheme (GTK_SOURCE_STYLE_SCHEME_CHOOSER (dlg->schemes_list),
-                                                         scheme);
+       if (scheme != NULL)
+       {
+               gtk_source_style_scheme_chooser_set_style_scheme (GTK_SOURCE_STYLE_SCHEME_CHOOSER 
(dlg->schemes_list),
+                                                                 scheme);
+       }
 
        /* Set initial widget sensitivity */
        set_buttons_sensisitivity_according_to_scheme (dlg, scheme);