[LyX/2.3.x] Set buffer correctly when changing math space type.

[Jean-Marc Lasgouttes]

commit 0e6cb4e599cc8aaf191200a963fa916274dc9b7f
Author: Jean-Marc Lasgouttes <lasgout...@lyx.org>
Date:   Thu Dec 13 10:27:20 2018 +0100

    Set buffer correctly when changing math space type.
    
    Fixes bug #7747.
    
    (cherry picked from commit 2ec25c8eef8c9acca3cb572800eab933c8564831)
---
 src/mathed/InsetMathSpace.cpp |    2 ++
 status.23x                    |    1 +
 2 files changed, 3 insertions(+), 0 deletions(-)

diff --git a/src/mathed/InsetMathSpace.cpp b/src/mathed/InsetMathSpace.cpp
index 88aae1d..79a4314 100644
--- a/src/mathed/InsetMathSpace.cpp
+++ b/src/mathed/InsetMathSpace.cpp
@@ -320,9 +320,11 @@ void InsetMathSpace::doDispatch(Cursor & cur, FuncRequest 
& cmd)
        case LFUN_INSET_MODIFY:
                if (cmd.getArg(0) == "mathspace") {
                        MathData ar;
+                       Buffer * buf = buffer_;
                        if (createInsetMath_fromDialogStr(cmd.argument(), ar)) {
                                cur.recordUndo();
                                *this = *ar[0].nucleus()->asSpaceInset();
+                               buffer_ = buf;
                                break;
                        }
                }
diff --git a/status.23x b/status.23x
index 8eaa54b..4f50e5c 100644
--- a/status.23x
+++ b/status.23x
@@ -63,6 +63,7 @@ What's new
 
 - Do not swallow backspaces in custom viewer/editor paths (bug 9622).
 
+- Fix broken space dialog in mathed (bug 7747).
 
 * INTERNALS