From 5d95d1143762a72e7cfe9c384c9d5752f6b888c2 Mon Sep 17 00:00:00 2001
From: Ghostkeeper <rubend@tutanota.com>
Date: Wed, 5 Dec 2018 09:52:43 +0100
Subject: [PATCH] Use setCurrentIndex to switch tabs at activeExtruderChanged

This fixes a mysterious segfault. We still don't know why the segfault occurred though. All we know is that QML logs something about a binding loop on currentIndex, and Qt logs something about removing range [-1 through 0] from VisualItemModel. When the tab bar is then made visible, Cura crashes. It is a nondeterministic crash. After this change, we are not seeing it any more (but with any nondeterministic bug, it's hard to verify that it was actually fixed).

Contributes to issue CURA-5876.
---
 .../ConfigurationMenu/CustomConfiguration.qml      | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/resources/qml/Menus/ConfigurationMenu/CustomConfiguration.qml b/resources/qml/Menus/ConfigurationMenu/CustomConfiguration.qml
index 2667c837ba..18c2dabb0f 100644
--- a/resources/qml/Menus/ConfigurationMenu/CustomConfiguration.qml
+++ b/resources/qml/Menus/ConfigurationMenu/CustomConfiguration.qml
@@ -42,8 +42,6 @@ Item
         anchors.topMargin: UM.Theme.getSize("default_margin").height
         visible: extrudersModel.count > 1
 
-        currentIndex: Math.max(Cura.ExtruderManager.activeExtruderIndex, 0)
-
         Repeater
         {
             id: repeater
@@ -68,6 +66,18 @@ Item
             }
         }
 
+        //When active extruder changes for some other reason, switch tabs.
+        //Don't directly link currentIndex to Cura.ExtruderManager.activeExtruderIndex!
+        //This causes a segfault in Qt 5.11. Something with VisualItemModel removing index -1. We have to use setCurrentIndex instead.
+        Connections
+        {
+            target: Cura.ExtruderManager
+            onActiveExtruderChanged:
+            {
+                tabBar.setCurrentIndex(Cura.ExtruderManager.activeExtruderIndex);
+            }
+        }
+
         //When the model of the extruders is rebuilt, the list of extruders is briefly emptied and rebuilt.
         //This causes the currentIndex of the tab to be in an invalid position which resets it to 0.
         //Therefore we need to change it back to what it was: The active extruder index.