From 875ecf7827aa107a18ce9bf14254d58d8676525e Mon Sep 17 00:00:00 2001
From: lethosor <lethosor@gmail.com>
Date: Sat, 14 Nov 2015 21:48:51 -0500
Subject: [PATCH] Update Core::top_viewscreen before calling state change
 handlers

This was previously done right before SC_VIEWSCREEN_CHANGED events
were handled, meaning that code handling earlier events that used
top_viewscreen (rather than getCurViewscreen()) could refer to an
invalid viewscreen, i.e. in the tick after it was deleted.

Fixes #747
---
 library/Core.cpp | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/library/Core.cpp b/library/Core.cpp
index 63357b145..a932e49e7 100644
--- a/library/Core.cpp
+++ b/library/Core.cpp
@@ -1721,6 +1721,14 @@ void Core::doUpdate(color_ostream &out, bool first_update)
             screen = screen->child;
     }
 
+    // detect if the viewscreen changed, and trigger events later
+    bool vs_changed = false;
+    if (screen != top_viewscreen)
+    {
+        top_viewscreen = screen;
+        vs_changed = true;
+    }
+
     bool is_load_save =
         strict_virtual_cast<df::viewscreen_game_cleanerst>(screen) ||
         strict_virtual_cast<df::viewscreen_loadgamest>(screen) ||
@@ -1770,12 +1778,8 @@ void Core::doUpdate(color_ostream &out, bool first_update)
         }
     }
 
-    // detect if the viewscreen changed
-    if (screen != top_viewscreen)
-    {
-        top_viewscreen = screen;
+    if (vs_changed)
         onStateChange(out, SC_VIEWSCREEN_CHANGED);
-    }
 
     if (df::global::pause_state)
     {