Index: gnome-shell-45.0/js/ui/status/keyboard.js
===================================================================
--- gnome-shell-45.0.orig/js/ui/status/keyboard.js
+++ gnome-shell-45.0/js/ui/status/keyboard.js
@@ -274,6 +274,39 @@ class InputSourceSessionSettings extends
         this._settings.connect(`changed::${this._KEY_INPUT_SOURCES}`, this._emitInputSourcesChanged.bind(this));
         this._settings.connect(`changed::${this._KEY_KEYBOARD_OPTIONS}`, this._emitKeyboardOptionsChanged.bind(this));
         this._settings.connect(`changed::${this._KEY_PER_WINDOW}`, this._emitPerWindowChanged.bind(this));
+
+        let sources = this._settings.get_value(this._KEY_INPUT_SOURCES);
+        let nSources = sources.n_children();
+        let sourcesList = [];
+
+        if (nSources <= 1) {
+            if (GLib.getenv('LANG') == 'zh_CN.UTF-8') {
+                log('Set default input method in Chinese language env.');
+                sourcesList.push(['xkb', 'cn']);
+                sourcesList.push([ "ibus", "libpinyin" ]);
+
+                let params = GLib.Variant.new('a(ss)', sourcesList);
+                this._settings.set_value(this._KEY_INPUT_SOURCES, params);
+            }
+
+            else if (GLib.getenv('LANG') == 'ja_JP.UTF-8') {
+                log('Set default input method in Japanese language env.');
+                sourcesList.push([ "ibus", "mozc-jp" ]);
+                sourcesList.push(['xkb', 'jp']);
+
+                let params = GLib.Variant.new('a(ss)', sourcesList);
+                this._settings.set_value(this._KEY_INPUT_SOURCES, params);
+            }
+
+            else if (GLib.getenv('LANG') == 'ko_KR.UTF-8') {
+                log('Set default input method in Korean language env.');
+                sourcesList.push(['xkb', 'kr']);
+                sourcesList.push([ "ibus", "hangul" ]);
+
+                let params = GLib.Variant.new('a(ss)', sourcesList);
+                this._settings.set_value(this._KEY_INPUT_SOURCES, params);
+            }
+        }
     }
 
     _getSourcesList(key) {