From 0be0f08afa953d850b504e22dc7a66dfd9573dfd Mon Sep 17 00:00:00 2001
From: Mark Liversedge <liversedge@gmail.com>
Date: Fri, 20 Jun 2014 17:24:41 +0100
Subject: [PATCH] Fix LTMCanvasPicker SEGV on delete tab

.. not always, but sometimes !
---
 src/LTMCanvasPicker.cpp | 7 +++----
 src/LTMCanvasPicker.h   | 2 ++
 2 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/src/LTMCanvasPicker.cpp b/src/LTMCanvasPicker.cpp
index 4c80b6736..c0f63a977 100644
--- a/src/LTMCanvasPicker.cpp
+++ b/src/LTMCanvasPicker.cpp
@@ -19,8 +19,7 @@ LTMCanvasPicker::LTMCanvasPicker(QwtPlot *plot):
     d_selectedCurve(NULL),
     d_selectedPoint(-1)
 {
-    QwtPlotCanvas *canvas = static_cast<QwtPlotCanvas*>(plot->canvas());
-
+    canvas = static_cast<QwtPlotCanvas*>(plot->canvas());
     canvas->installEventFilter(this);
 
 
@@ -41,8 +40,8 @@ bool LTMCanvasPicker::event(QEvent *e)
 
 bool LTMCanvasPicker::eventFilter(QObject *object, QEvent *e)
 {
-    if ( object != (QObject *)plot()->canvas() )
-        return false;
+    // for our canvas ?
+    if (object != canvas) return false;
 
     switch(e->type())
     {
diff --git a/src/LTMCanvasPicker.h b/src/LTMCanvasPicker.h
index 33c780e19..26742038c 100644
--- a/src/LTMCanvasPicker.h
+++ b/src/LTMCanvasPicker.h
@@ -11,6 +11,7 @@ class QPoint;
 class QCustomEvent;
 class QwtPlot;
 class QwtPlotCurve;
+class QwtPlotCanvas;
 
 class LTMCanvasPicker: public QObject
 {
@@ -27,6 +28,7 @@ signals:
     void pointHover(QwtPlotCurve *, int);
 
 private:
+    QwtPlotCanvas *canvas;
     void select(const QPoint &, bool);
     QwtPlot *plot() { return (QwtPlot *)parent(); }
     const QwtPlot *plot() const { return (QwtPlot *)parent(); }