From 6a9a13c50630c86908f70fe162c9b66469ee715c Mon Sep 17 00:00:00 2001
From: Charles Gagnon <charlesg99@outlook.com>
Date: Wed, 6 Apr 2022 13:51:55 -0400
Subject: [PATCH] Reuse same monitor as primary if not GS primary

---
 panelManager.js | 31 +++++++++++++++++++++++++------
 prefs.js        |  2 +-
 2 files changed, 26 insertions(+), 7 deletions(-)

diff --git a/panelManager.js b/panelManager.js
index 535dd9d1..59a456b5 100755
--- a/panelManager.js
+++ b/panelManager.js
@@ -249,7 +249,7 @@ var PanelManager = class {
                 'monitors-changed', 
                 () => {
                     if (Main.layoutManager.primaryMonitor) {
-                        this._saveMonitors();
+                        this._saveMonitors(true);
                         this._reset();
                     }
                 }
@@ -400,17 +400,36 @@ var PanelManager = class {
         }
     }
 
-    _saveMonitors() {
+    _saveMonitors(savePrimaryChange) {
         //Mutter meta_monitor_manager_get_primary_monitor (global.display.get_primary_monitor()) doesn't return the same
         //monitor as GDK gdk_screen_get_primary_monitor (imports.gi.Gdk.Screen.get_default().get_primary_monitor()).
         //Since the Mutter function is what's used in gnome-shell and we can't access it from the settings dialog, store 
         //the monitors information in a setting so we can use the same monitor indexes as the ones in gnome-shell
+        let keyMonitors = 'available-monitors';
         let primaryIndex = Main.layoutManager.primaryIndex;
-        let monitors = [primaryIndex];
+        let newMonitors = [primaryIndex];
 
-        Main.layoutManager.monitors.filter(m => m.index != primaryIndex).forEach(m => monitors.push(m.index));
-        Me.settings.set_value('available-monitors', new GLib.Variant('ai', monitors));
-        Me.settings.set_int('primary-monitor', primaryIndex);
+        Main.layoutManager.monitors.filter(m => m.index != primaryIndex).forEach(m => newMonitors.push(m.index));
+        
+        if (savePrimaryChange) {
+            let keyPrimary = 'primary-monitor';
+            let savedMonitors = Me.settings.get_value(keyMonitors).deep_unpack();
+            let dtpPrimaryIndex = Me.settings.get_int(keyPrimary);
+            let newDtpPrimaryIndex = primaryIndex;
+
+            if (savedMonitors[0] != dtpPrimaryIndex) {
+                // dash to panel primary wasn't the gnome-shell primary (first index of available-monitors)
+                let savedIndex = savedMonitors.indexOf(dtpPrimaryIndex)
+
+                // default to primary if it was set to a monitor that is no longer available
+                newDtpPrimaryIndex = newMonitors[savedIndex];
+                newDtpPrimaryIndex = newDtpPrimaryIndex == null ? primaryIndex : newDtpPrimaryIndex;
+            }
+            
+            Me.settings.set_int(keyPrimary, newDtpPrimaryIndex);
+        }
+
+        Me.settings.set_value(keyMonitors, new GLib.Variant('ai', newMonitors));
     }
 
     checkIfFocusedMonitor(monitor) {
diff --git a/prefs.js b/prefs.js
index c07e8a96..4190a853 100644
--- a/prefs.js
+++ b/prefs.js
@@ -883,7 +883,7 @@ const Preferences = class {
         this._updateVerticalRelatedOptions();
         
         for (let i = 0; i < this.monitors.length; ++i) {
-            //the primary index is the first one in the "available-monitors" setting
+            //the gnome-shell primary index is the first one in the "available-monitors" setting
             let label = !i ? _('Primary monitor') : _('Monitor ') + (i + 1);
 
             this._builder.get_object('multimon_primary_combo').append_text(label);