Use flat style for scale lock button

nyalldawson · nyalldawson · commit 57314a1ae912 · 2016-07-19T17:25:18.000+10:00
(cherry-picked from b220d66)
diff --git a/src/app/qgsstatusbarscalewidget.cpp b/src/app/qgsstatusbarscalewidget.cpp
@@ -54,6 +54,7 @@ QgsStatusBarScaleWidget::QgsStatusBarScaleWidget( QgsMapCanvas *canvas, QWidget
   mLockButton->setToolTip( tr( "Lock the scale to use magnifier to zoom in or out." ) );
   mLockButton->setCheckable( true );
   mLockButton->setChecked( false );
+  mLockButton->setAutoRaise( true );
 
   // layout
   mLayout = new QHBoxLayout( this );
