kTrackInfoWidth was misleadingly named...

... keep the name, but change the value to be what it really says:
the proper width of the track control panel, agreeing with the hit-test
area, NOT including the left margin

And change places where the constant was used, adding the margin back again.

src/TrackPanel.cpp

@@ -111,9 +111,8 @@ left channel, are used for the channel separator.
 "Margin" is a term used for inset plus border (top and left) or inset plus
 shadow plus border (right and bottom).
 
-TrackInfo::GetTrackInfoWidth() == GetVRulerOffset()
+GetVRulerOffset() counts columns from the left edge up to and including
-counts columns from the left edge up to and including controls, and is a
+controls, and is a constant.
-constant.
 
 GetVRulerWidth() is variable -- all tracks have the same ruler width at any
 time, but that width may be adjusted when tracks change their vertical scales.
@@ -1664,7 +1663,7 @@ void TrackPanel::DrawOutside
    }
 
    // Draw things within the track control panel
-   rect.width = kTrackInfoWidth - kLeftMargin;
+   rect.width = kTrackInfoWidth;
    TrackInfo::DrawItems( context, rect, *t );
 
    //mTrackInfo.DrawBordersWithin( dc, rect, *t );
@@ -2067,7 +2066,7 @@ struct LabeledChannelGroup final : TrackPanelGroup {
    Subdivision Children( const wxRect &rect ) override
    { return { Axis::X, Refinement{
       { rect.GetLeft(), mpTrack->GetTrackControl() },
-      { kTrackInfoWidth,
+      { rect.GetLeft() + kTrackInfoWidth,
         std::make_shared< ChannelGroup >( mpTrack, mLeftOffset ) }
    } }; }
    std::shared_ptr< Track > mpTrack;
@@ -2313,11 +2312,6 @@ void TrackInfo::ReCreateSliders( wxWindow *pParent ){
 
 }
 
-int TrackInfo::GetTrackInfoWidth()
-{
-   return kTrackInfoWidth;
-}
-
 void TrackInfo::GetCloseBoxHorizontalBounds( const wxRect & rect, wxRect &dest )
 {
    dest.x = rect.x;
@@ -2670,7 +2664,10 @@ void TrackInfo::UpdatePrefs( wxWindow *pParent )
    int fontSize = 10;
    gFont.Create(fontSize, wxFONTFAMILY_SWISS, wxFONTSTYLE_NORMAL, wxFONTWEIGHT_NORMAL);
 
-   int allowableWidth = GetTrackInfoWidth() - 2; // 2 to allow for left/right borders
+   int allowableWidth =
+      // PRL:  was it correct to include the margin?
+      ( kTrackInfoWidth + kLeftMargin )
+         - 2; // 2 to allow for left/right borders
    int textWidth, textHeight;
    do {
       gFont.SetPointSize(fontSize);

src/TrackPanel.h

@@ -143,7 +143,6 @@ namespace TrackInfo
       ( TrackPanelDrawingContext &context,
         const wxRect &rect, const Track *pTrack );
 
-   int GetTrackInfoWidth();
    void SetTrackInfoFont(wxDC *dc);
 
 
@@ -216,6 +215,37 @@ namespace TrackInfo
 const int DragThreshold = 3;// Anything over 3 pixels is a drag, else a click.
 
 
+// See big pictorial comment in TrackPanel for explanation of these numbers
+enum : int {
+   kLeftInset = 4,
+   kRightInset = kLeftInset,
+   kTopInset = 4,
+   kShadowThickness = 1,
+   kBorderThickness = 1,
+   kTopMargin = kTopInset + kBorderThickness,
+   kBottomMargin = kShadowThickness + kBorderThickness,
+   kLeftMargin = kLeftInset + kBorderThickness,
+   kRightMargin = kRightInset + kShadowThickness + kBorderThickness,
+   kSeparatorThickness = kBottomMargin + kTopMargin,
+};
+
+enum : int {
+   kTrackInfoWidth = 100 - kLeftMargin,
+   kTrackInfoBtnSize = 18, // widely used dimension, usually height
+   kTrackInfoSliderHeight = 25,
+   kTrackInfoSliderWidth = 84,
+   kTrackInfoSliderAllowance = 5,
+   kTrackInfoSliderExtra = 5,
+};
+
+#ifdef USE_MIDI
+enum : int {
+   // PRL:  was it correct to include the margin?
+   kMidiCellWidth = ( ( kTrackInfoWidth + kLeftMargin ) / 4) - 2,
+   kMidiCellHeight = kTrackInfoBtnSize
+};
+#endif
+
 class AUDACITY_DLL_API TrackPanel final : public CellularPanel {
 
  public:
@@ -322,11 +352,11 @@ protected:
    std::shared_ptr<TrackPanelNode> Root() override;
 
    int GetVRulerWidth() const;
-   int GetVRulerOffset() const { return TrackInfo::GetTrackInfoWidth(); }
+   int GetVRulerOffset() const { return kTrackInfoWidth + kLeftMargin; }
 
 public:
    int GetLabelWidth() const
-      { return TrackInfo::GetTrackInfoWidth() + GetVRulerWidth(); }
+      { return GetVRulerOffset() + GetVRulerWidth(); }
 
 // JKC Nov-2011: These four functions only used from within a dll such as mod-track-panel
 // They work around some messy problems with constructors.
@@ -476,34 +506,4 @@ struct IsVisibleTrack
    wxRect mPanelRect;
 };
 
-// See big pictorial comment in TrackPanel for explanation of these numbers
-enum : int {
-   kLeftInset = 4,
-   kRightInset = kLeftInset,
-   kTopInset = 4,
-   kShadowThickness = 1,
-   kBorderThickness = 1,
-   kTopMargin = kTopInset + kBorderThickness,
-   kBottomMargin = kShadowThickness + kBorderThickness,
-   kLeftMargin = kLeftInset + kBorderThickness,
-   kRightMargin = kRightInset + kShadowThickness + kBorderThickness,
-   kSeparatorThickness = kBottomMargin + kTopMargin,
-};
-
-enum : int {
-   kTrackInfoWidth = 100,
-   kTrackInfoBtnSize = 18, // widely used dimension, usually height
-   kTrackInfoSliderHeight = 25,
-   kTrackInfoSliderWidth = 84,
-   kTrackInfoSliderAllowance = 5,
-   kTrackInfoSliderExtra = 5,
-};
-
-#ifdef USE_MIDI
-enum : int {
-   kMidiCellWidth = (kTrackInfoWidth / 4) - 2,
-   kMidiCellHeight = kTrackInfoBtnSize
-};
-#endif
-
 #endif