From bca2d063bb8fe763bfc8bfd4e14c210dab2986ba Mon Sep 17 00:00:00 2001
From: Paul Cornett <paulcor@users.noreply.github.com>
Date: Sun, 26 Nov 2017 00:00:44 -0800
Subject: [PATCH] Avoid using NULL style provider

Fixes assertions with wxNotebook
---
 src/gtk/window.cpp | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/src/gtk/window.cpp b/src/gtk/window.cpp
index 241c3db820..5b1b0605ac 100644
--- a/src/gtk/window.cpp
+++ b/src/gtk/window.cpp
@@ -4690,9 +4690,12 @@ void wxWindowGTK::DoApplyWidgetStyle(GtkRcStyle *style)
 void wxWindowGTK::GTKApplyStyle(GtkWidget* widget, GtkRcStyle* WXUNUSED_IN_GTK3(style))
 {
 #ifdef __WXGTK3__
-    GtkStyleContext* context = gtk_widget_get_style_context(widget);
-    gtk_style_context_add_provider(context,
-        m_styleProvider, GTK_STYLE_PROVIDER_PRIORITY_APPLICATION);
+    if (m_styleProvider)
+    {
+        GtkStyleContext* context = gtk_widget_get_style_context(widget);
+        gtk_style_context_add_provider(context,
+            m_styleProvider, GTK_STYLE_PROVIDER_PRIORITY_APPLICATION);
+    }
 #else
     gtk_widget_modify_style(widget, style);
 #endif