From 57ff92b20c01ce6da39475858775619a532e106b Mon Sep 17 00:00:00 2001
From: James Crook <james.k.crook@gmail.com>
Date: Thu, 9 Jan 2020 15:56:00 +0000
Subject: [PATCH] Bug 2275 - Crash when unchecking Multi-view with neither of
 the views checked

---
 .../wavetrack/ui/WaveTrackView.cpp            | 39 ++++++++++++++-----
 1 file changed, 29 insertions(+), 10 deletions(-)

diff --git a/src/tracks/playabletrack/wavetrack/ui/WaveTrackView.cpp b/src/tracks/playabletrack/wavetrack/ui/WaveTrackView.cpp
index 5491f10ee..10f1f29b8 100644
--- a/src/tracks/playabletrack/wavetrack/ui/WaveTrackView.cpp
+++ b/src/tracks/playabletrack/wavetrack/ui/WaveTrackView.cpp
@@ -559,31 +559,50 @@ void WaveTrackView::ToggleSubView(WaveTrackDisplay display)
       return false;
    } ) ) {
       auto &foundPlacement = mPlacements[found];
+      auto index = foundPlacement.index;
+      unsigned nn = 0;
+
+      // if found and active, deactivate it..
       if ( foundPlacement.fraction > 0.0 ) {
-         auto index = foundPlacement.index;
-         foundPlacement = { -1, 0.0 };
-         if (index >= 0) {
-            for ( auto &placement : mPlacements ) {
-               if ( placement.index > index )
-                  --placement.index;
+         for (auto &placement : mPlacements) {
+            if (placement.fraction > 0.0 && placement.index >= 0) {
+               nn++;
+            }
+         }
+         // if removing the last one, then don't!
+         // Switch to radio-button view instead.
+         if (nn <= 1) {
+            DoSetDisplay(display, 1.0);
+            SetMultiView(false);
+         }
+         else
+         {
+            foundPlacement = { -1, 0.0 };
+            if (index >= 0) {
+               for (auto &placement : mPlacements) {
+                  if (placement.index > index)
+                     --placement.index;
+               }
             }
          }
       }
+      // else found and zero size, so add it on the bottom.
       else {
          float total = 0;
          int greatest = -1;
-         unsigned nn = 0;
-         int removedIndex = foundPlacement.index;
          for ( auto &placement : mPlacements ) {
             if ( placement.fraction >= 0.0 && placement.index >= 0 ) {
                // renumber in case there's an item removed.
-               if( (removedIndex >= 0) && (placement.index >= removedIndex))
-                  placement.index -= 1;
+               if( (index >= 0) && (placement.index >= index))
+                  --placement.index;
                total += placement.fraction;
                greatest = std::max( greatest, placement.index );
                ++nn;
             }
          }
+         // 
+         if ( index >= 0)
+            --nn;
          // Turn on the sub-view, putting it lowest, and with average of the
          // heights of the other sub-views
          foundPlacement = { greatest + 1, total / nn };