Solved crash when using marker without any clip loaded.

src/GUI/PreviewRuler.cpp

@@ -30,7 +30,7 @@
 PreviewRuler::PreviewRuler( QWidget* parent ) :
         QWidget( parent ),
         m_renderer( NULL ),
-        m_frame( NULL )
+        m_frame( 0 )
 {
     setMouseTracking( true );
     m_isSliding = false;
@@ -141,34 +141,35 @@ void PreviewRuler::paintEvent( QPaintEvent * event )
                     painter.drawLine( QLineF( r.left() + step * spacing, r.height() - MARK_LARGE, r.left() + step * spacing, r.bottom() ) );
             }
         }
-    }
 
-    // Draw the markers (if any)
-    painter.setPen( QPen( Qt::green, 2 ) );
+        // Draw the markers (if any)
+        painter.setPen( QPen( Qt::green, 2 ) );
 
-    if ( m_markerStart > MARKER_DEFAULT )
-    {
-        int markerPos = m_markerStart * width() / m_renderer->getLength();
-        QPolygon marker( 4 );
-        marker.setPoints( 4,
-                          markerPos + 8,    1,
-                          markerPos,        1,
-                          markerPos,        20,
-                          markerPos + 8,    20 );
-        painter.drawPolyline( marker );
-    }
-    if ( m_markerStop > MARKER_DEFAULT )
-    {
-        int markerPos = m_markerStop * width() / m_renderer->getLength();
-        QPolygon marker( 4 );
-        marker.setPoints( 4,
-                          markerPos - 8,    1,
-                          markerPos,        1,
-                          markerPos,        20,
-                          markerPos - 8,    20 );
-        painter.drawPolyline( marker );
+        if ( m_markerStart > MARKER_DEFAULT )
+        {
+            int markerPos = m_markerStart * width() / m_renderer->getLength();
+            QPolygon marker( 4 );
+            marker.setPoints( 4,
+                              markerPos + 8,    1,
+                              markerPos,        1,
+                              markerPos,        20,
+                              markerPos + 8,    20 );
+            painter.drawPolyline( marker );
+        }
+        if ( m_markerStop > MARKER_DEFAULT )
+        {
+            int markerPos = m_markerStop * width() / m_renderer->getLength();
+            QPolygon marker( 4 );
+            marker.setPoints( 4,
+                              markerPos - 8,    1,
+                              markerPos,        1,
+                              markerPos,        20,
+                              markerPos - 8,    20 );
+            painter.drawPolyline( marker );
+        }
     }
 
+
     // Draw the pointer
     painter.setRenderHint( QPainter::Antialiasing );
     painter.setPen( QPen( Qt::white ) );