From 7688fdc94fa98e7c084c18fc687d1f568403a4e4 Mon Sep 17 00:00:00 2001
From: Jeff Young <jeff@rokeby.ie>
Date: Tue, 2 Feb 2021 01:05:48 +0000
Subject: [PATCH] Hack to prevent multiple simulation commands from stacking
 up.

Can happen if someone hammers away on the probe and/or tune tools
without ever mousing over the schematic in between.

*May* fix the below bug.

Fixes https://gitlab.com/kicad/code/kicad/issues/6876
---
 common/tool/tool_event.cpp  | 7 +++++++
 include/tool/tool_event.h   | 5 +++++
 include/tool/tool_manager.h | 5 +++++
 3 files changed, 17 insertions(+)

diff --git a/common/tool/tool_event.cpp b/common/tool/tool_event.cpp
index c9a1d4b4a4..ec640a0c4a 100644
--- a/common/tool/tool_event.cpp
+++ b/common/tool/tool_event.cpp
@@ -219,3 +219,10 @@ bool TOOL_EVENT::IsMoveTool() const
     return( m_commandStr.is_initialized()
                 && m_commandStr.get().find( "InteractiveMove" ) != GetCommandStr()->npos );
 }
+
+
+bool TOOL_EVENT::IsSimulator() const
+{
+    return( m_commandStr.is_initialized()
+                && m_commandStr.get().find( "Simulation" ) != GetCommandStr()->npos );
+}
\ No newline at end of file
diff --git a/include/tool/tool_event.h b/include/tool/tool_event.h
index 22f993fb9c..9337e57744 100644
--- a/include/tool/tool_event.h
+++ b/include/tool/tool_event.h
@@ -418,6 +418,11 @@ public:
      */
     bool IsMoveTool() const;
 
+    /**
+     * Indicate if the event is from the simulator.
+     */
+    bool IsSimulator() const;
+
     /**
      * Return a non-standard parameter assigned to the event. Its meaning depends on the
      * target tool.
diff --git a/include/tool/tool_manager.h b/include/tool/tool_manager.h
index 06632b3d06..aac2248455 100644
--- a/include/tool/tool_manager.h
+++ b/include/tool/tool_manager.h
@@ -266,6 +266,11 @@ public:
      */
     inline void PostEvent( const TOOL_EVENT& aEvent )
     {
+        // Horrific hack, but it's a crash bug.  Don't let inter-frame commands stack up
+        // waiting to be processed.
+        if( aEvent.IsSimulator() && m_eventQueue.back().IsSimulator() )
+            m_eventQueue.pop_back();
+
         m_eventQueue.push_back( aEvent );
     }