[gnote: 1/2] Use $XDG_CURRENT_DESKTOP for CSD decision

[Aurimas Černius <aurimasc src gnome org>]

commit 0102c770052fe6e6ad25fb5a2b8e44ceb7a76e9e
Author: Will Thompson <wjt endlessm com>
Date:   Sat Mar 14 22:14:14 2020 +0000

    Use $XDG_CURRENT_DESKTOP for CSD decision
    
    Previously, the automatic decision for whether to use client-side
    decorations was made by examining the $DESKTOP_SESSION variable. This
    entails adding new entries to the default value for any new desktop,
    even if it is derived from one already on the list.
    
    $XDG_CURRENT_DESKTOP is defined by the Desktop Entry Specification[0],
    in passing, while defining the OnlyShowIn/NotShowIn keys:
    
    > If $XDG_CURRENT_DESKTOP is set then it contains a colon-separated list
    > of strings. In order, each string is considered. If a matching entry is
    > found in OnlyShowIn then the desktop file is shown. If an entry is
    > found in NotShowIn then the desktop file is not shown. If none of the
    > strings match then the default action is taken (as above).
    
    On Ubuntu, $XDG_CURRENT_DESKTOP is "ubuntu:GNOME". Similarly, in Endless
    OS 3.8.0, it will be "endless:GNOME". This is a more scalable way to
    detect a "GNOME-like" desktop than a gradually-expanding list of
    substring matches on the desktop session name.
    
    With this change, Gnote correctly displays without server-side
    decorations on Endless OS 3.8.0.
    
    [0] 
https://specifications.freedesktop.org/desktop-entry-spec/desktop-entry-spec-latest.html#recognized-keys

 src/mainwindow.cpp | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)
---
diff --git a/src/mainwindow.cpp b/src/mainwindow.cpp
index 92cbe078..e415bca4 100644
--- a/src/mainwindow.cpp
+++ b/src/mainwindow.cpp
@@ -120,13 +120,17 @@ bool MainWindow::use_client_side_decorations(Preferences & prefs)
       s_use_client_side_decorations = 0;
       std::vector<Glib::ustring> desktops;
       sharp::string_split(desktops, setting, ",");
-      const char *current_desktop = std::getenv("DESKTOP_SESSION");
+      const char *current_desktop = std::getenv("XDG_CURRENT_DESKTOP");
       if (current_desktop) {
-        Glib::ustring current_de = Glib::ustring(current_desktop).lowercase();
-        for(const Glib::ustring & de : desktops) {
-          Glib::ustring denv = Glib::ustring(de).lowercase();
-          if(current_de.find(denv) != Glib::ustring::npos) {
-            s_use_client_side_decorations = 1;
+        std::vector<Glib::ustring> current_desktops;
+        sharp::string_split(current_desktops, current_desktop, ":");
+        for(const Glib::ustring & cd : current_desktops) {
+          Glib::ustring current_de = cd.lowercase();
+          for(const Glib::ustring & de : desktops) {
+            if (current_de == de) {
+              s_use_client_side_decorations = 1;
+              return s_use_client_side_decorations;
+            }
           }
         }
       }