timeline: snap pointer and import operations to timebase

If frame rates are mixed, ensures that video doesn't end up falling or ending on half frames which potentially make the entire sequence awkward

app/widget/timelinewidget/timelinewidget.cpp

@@ -353,14 +353,6 @@ void TimelineWidget::PasteNodesFromClipboardInternal(QXmlStreamReader *reader, X
   }
 }
 
-rational TimelineWidget::GetToolTipTimebase() const
-{
-  if (GetConnectedNode() && use_audio_time_units_) {
-    return GetConnectedNode()->audio_params().time_base();
-  }
-  return timebase();
-}
-
 void TimelineWidget::SelectAll()
 {
   QVector<Block*> newly_selected_blocks;
@@ -1211,6 +1203,11 @@ TimelineView *TimelineWidget::GetFirstTimelineView()
   return views_.first()->view();
 }
 
+rational TimelineWidget::GetTimebaseForTrackType(Timeline::TrackType type)
+{
+  return views_.at(type)->view()->timebase();
+}
+
 const QRect& TimelineWidget::GetRubberBandGeometry() const
 {
   return rubberband_.geometry();