Timeline: investigate how to handle profile rebuilding

as it turns out, the core problem is that we need a way to detect and signal
structural changes to the logical UI model

src/stage/timeline/body-canvas-widget.cpp

@@ -235,13 +235,6 @@ namespace timeline {
   
   
   
-  TimelineCanvas::TimelineCanvas (_Renderer groundingFac, _Renderer overlayFac)
-    : Gtk::Layout{}
-    , renderGrounding_{groundingFac}
-    , renderOverlay_{overlayFac}
-    { }
-  
-  
   
   BodyCanvasWidget::~BodyCanvasWidget() { }
   
@@ -308,6 +301,15 @@ namespace timeline {
   }
   
   
+  
+  
+  TimelineCanvas::TimelineCanvas (_Renderer groundingFac, _Renderer overlayFac)
+    : Gtk::Layout{}
+    , renderGrounding_{groundingFac}
+    , renderOverlay_{overlayFac}
+    { }
+  
+  
   /**
    * Custom drawing of the timeline content area.
    * The inherited `Gtk::Layout::on_raw(Context)` handles all drawing of child widgets placed onto the virtual canvas.

src/stage/timeline/track-body.cpp

@@ -118,9 +118,8 @@ namespace timeline {
   TrackBody::establishTrackSpace (TrackProfile& profile)
   {
     bool topLevel = isnil (profile);
-    
     if (topLevel)
-      profile.append_prelude(rulers_.size());
+      profile.append_prelude (rulers_.size());
     
     for (auto& ruler : rulers_)
       {
@@ -130,7 +129,7 @@ namespace timeline {
           profile.append_gap (gapHeight);
       }
     profile.append_content (this->contentHeight_);
-    if (not isnil(subTracks_))
+    if (not isnil (subTracks_))
       {
         profile.addSlopeDown();
         for (TrackBody* subTrack : subTracks_)
@@ -139,7 +138,7 @@ namespace timeline {
       }
     
     if (topLevel)
-      profile.append_coda(TIMELINE_BOTTOM_PADDING_px);
+      profile.append_coda (TIMELINE_BOTTOM_PADDING_px);
   }
   
   

src/stage/timeline/track-presenter.cpp

@@ -23,6 +23,10 @@
 
 /** @file track-presenter.cpp
  ** Implementation details of track presentation management.
+ ** Especially here we define the model binding of all sub-elements belonging
+ ** to a given track. The TrackPresenter::buildMutator() implementation hooks up
+ ** the necessary callbacks, to allow adding and removing of sub elements and properties
+ ** of a track, by sending appropriate _mutation messages_ over the stage::UiBus.
  ** 
  ** @todo WIP-WIP-WIP as of 12/2016
  ** @todo as of 10/2018 timeline display in the UI is rebuilt to match the architecture

src/stage/timeline/track-presenter.hpp

@@ -93,7 +93,7 @@ namespace timeline {
      ~DisplayFrame()
         {
           TODO ("cause the managed presentation elements to detach from their parents");
-        }
+        }                            ///////////////////////////////////TICKET #1198 -- clarify to what extent esp. the header widgets need to be actively removed from the display structure. Is it sufficient just to kill the TrackHeadWidget 
       
       void
       setTrackName (cuString& name)