From 2ec2ea5ac01fac665fe3014edd04a9bde4e25421 Mon Sep 17 00:00:00 2001
From: wmayer <wmayer@users.sourceforge.net>
Date: Wed, 15 Mar 2017 17:28:45 +0100
Subject: [PATCH] Qt5OpenGL: fix flickering on resize

---
 src/Gui/Quarter/QuarterWidget.cpp | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/src/Gui/Quarter/QuarterWidget.cpp b/src/Gui/Quarter/QuarterWidget.cpp
index 5c9f827068..905e512303 100644
--- a/src/Gui/Quarter/QuarterWidget.cpp
+++ b/src/Gui/Quarter/QuarterWidget.cpp
@@ -176,6 +176,7 @@ public:
                 logger->startLogging(QOpenGLDebugLogger::SynchronousLogging);
         }
 #endif
+        connect(this, &CustomGLWidget::resized, this, &CustomGLWidget::slotResized);
     }
     bool event(QEvent *e)
     {
@@ -199,6 +200,14 @@ public:
     {
         qDebug() << message;
     }
+    void showEvent(QShowEvent*)
+    {
+        update(); // force update when changing window mode
+    }
+    void slotResized()
+    {
+        update(); // fixes flickering on some systems
+    }
 };
 #else
 class CustomGLWidget : public QGLWidget {