From 787e925b5891ea44491648dfe3c58d7ec6c90689 Mon Sep 17 00:00:00 2001
From: Nyall Dawson <nyall.dawson@gmail.com>
Date: Thu, 11 Jun 2015 15:19:25 +1000
Subject: [PATCH] If graduated ranges are inconsistent or overlapping then
 don't allow changes via the histogram. Prevents ranges from getting even more
 mucked up.

---
 .../symbology-ng/qgsgraduatedhistogramwidget.cpp   | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/src/gui/symbology-ng/qgsgraduatedhistogramwidget.cpp b/src/gui/symbology-ng/qgsgraduatedhistogramwidget.cpp
index 1ae3d807ff4..1498f417b4b 100644
--- a/src/gui/symbology-ng/qgsgraduatedhistogramwidget.cpp
+++ b/src/gui/symbology-ng/qgsgraduatedhistogramwidget.cpp
@@ -82,11 +82,21 @@ void QgsGraduatedHistogramWidget::drawHistogram()
   if ( !mRenderer )
     return;
 
-  setGraduatedRanges( mRenderer->ranges() );
+  bool pickerEnabled = false;
+  if ( !mRenderer->rangesOverlap() && !mRenderer->rangesHaveGaps() && !mRenderer->ranges().isEmpty() )
+  {
+    setGraduatedRanges( mRenderer->ranges() );
+    pickerEnabled = true;
+  }
+  else
+  {
+    setGraduatedRanges( QgsRangeList() );
+  }
   QgsHistogramWidget::drawHistogram();
 
   // histo picker
-  mHistoPicker->setEnabled( true );
+  mHistoPicker->setEnabled( pickerEnabled );
+  mFilter->blockSignals( !pickerEnabled );
 }
 
 void QgsGraduatedHistogramWidget::mousePress( double value )