[LyX/master] Check for hidden dirty child on close

[Juergen Spitzmueller]

commit f87218bbb50e2043d3a052803cdef0bbcdcbc338
Author: Juergen Spitzmueller <sp...@lyx.org>
Date:   Mon Dec 17 09:11:34 2018 +0100

    Check for hidden dirty child on close
    
    Fixes: #11405
---
 src/frontends/qt4/GuiView.cpp |   10 +++++++---
 1 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/src/frontends/qt4/GuiView.cpp b/src/frontends/qt4/GuiView.cpp
index 56f4f7b..9d5f5dc 100644
--- a/src/frontends/qt4/GuiView.cpp
+++ b/src/frontends/qt4/GuiView.cpp
@@ -3069,9 +3069,13 @@ bool GuiView::closeBuffer(Buffer & buf)
                                        break;
                        } else {
                                // In this case the child buffer is open but 
hidden.
-                               // It therefore should not (MUST NOT) be dirty!
-                               LATTEST(child_buf->isClean());
-                               theBufferList().release(child_buf);
+                               // Even in this case, children can be dirty 
(e.g.,
+                               // after a label change in the master, see 
#11405).
+                               // Therefore, check this.
+                               if (saveBufferIfNeeded(*child_buf, false)) {
+                                       child_buf->removeAutosaveFile();
+                                       theBufferList().release(child_buf);
+                               }
                        }
                }
        }