[LyX/master] Do not crash when entering math in ct mode with merge dialog open.

[Richard Heck]

commit 9b6eea6ca516ded90a896324c01bdc0a2a20f5ba
Author: Juergen Spitzmueller <sp...@lyx.org>
Date:   Sun Mar 23 09:52:32 2014 +0100

    Do not crash when entering math in ct mode with merge dialog open.
    
    Fixes: #7685.

diff --git a/src/BufferView.cpp b/src/BufferView.cpp
index 2d3df5f..392f380 100644
--- a/src/BufferView.cpp
+++ b/src/BufferView.cpp
@@ -686,6 +686,10 @@ Change const BufferView::getCurrentChange() const
                return Change(Change::UNCHANGED);
 
        DocIterator dit = d->cursor_.selectionBegin();
+       // The selected content might have been changed (see #7685)
+       while (dit.inMathed())
+               // Find enclosing text cursor
+               dit.pop_back();
        return dit.paragraph().lookupChange(dit.pos());
 }