From 6ed23c2e7ddce0cb145569dc2b56648f851cbb05 Mon Sep 17 00:00:00 2001
From: wmayer <wmayer@users.sourceforge.net>
Date: Thu, 27 Jun 2024 18:35:40 +0200
Subject: [PATCH] Gui: Fix crash in QuarterWidgetP::removeFromCacheContext

Fixes #https://github.com/FreeCAD/FreeCAD/issues/14988
---
 src/Gui/Quarter/QuarterWidgetP.cpp | 19 ++++++++++++++-----
 1 file changed, 14 insertions(+), 5 deletions(-)

diff --git a/src/Gui/Quarter/QuarterWidgetP.cpp b/src/Gui/Quarter/QuarterWidgetP.cpp
index 5f3267e5c8..7771c4b79b 100644
--- a/src/Gui/Quarter/QuarterWidgetP.cpp
+++ b/src/Gui/Quarter/QuarterWidgetP.cpp
@@ -169,13 +169,22 @@ QuarterWidgetP::removeFromCacheContext(QuarterWidgetP_cachecontext * context, co
 
     for (int i = 0; i < cachecontext_list->getLength(); i++) {
       if ((*cachecontext_list)[i] == context) {
-        // set the context while calling destructingContext() (might trigger OpenGL calls)
-        const_cast<QtGLWidget*> (widget)->makeCurrent();
-        // fetch the cc_glglue context instance as a workaround for a bug fixed in Coin r12818
-        (void) cc_glglue_instance(context->id);
+        QtGLContext* glcontext = widget->context();
+        if (glcontext) {
+          // set the context while calling destructingContext() (might trigger OpenGL calls)
+          if (glcontext->isValid()) {
+            const_cast<QtGLWidget*> (widget)->makeCurrent();
+          }
+          // fetch the cc_glglue context instance as a workaround for a bug fixed in Coin r12818
+          (void) cc_glglue_instance(context->id);
+        }
         cachecontext_list->removeFast(i);
         SoContextHandler::destructingContext(context->id);
-        const_cast<QtGLWidget*> (widget)->doneCurrent();
+        if (glcontext) {
+          if (glcontext->isValid()) {
+            const_cast<QtGLWidget*> (widget)->doneCurrent();
+          }
+        }
         delete context;
         return;
       }