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

[Jean-Marc Lasgouttes]

commit 2ec25c8eef8c9acca3cb572800eab933c8564831
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.
---
 src/mathed/InsetMathSpace.cpp |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/src/mathed/InsetMathSpace.cpp b/src/mathed/InsetMathSpace.cpp
index 627664b..db09609 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;
                        }
                }