[LyX/master] Use isActive() instead of editable() in mathed.

[Jean-Marc Lasgouttes]

commit c2f785bdcc769f0c3ab0de186291c810f3f0875d
Author: Jean-Marc Lasgouttes <lasgout...@lyx.org>
Date:   Sun Mar 22 21:40:52 2015 +0100

    Use isActive() instead of editable() in mathed.
    
    Fixes crash introduced in [17e435c4/lyxgit].
    
    editable() is more related to Texted. It is false for closed collapsable 
insets
    Eventually the two methods should be merged.

diff --git a/src/DocIterator.cpp b/src/DocIterator.cpp
index 750479f..4dbd261 100644
--- a/src/DocIterator.cpp
+++ b/src/DocIterator.cpp
@@ -577,8 +577,9 @@ void DocIterator::sanitize()
                        fixIfBroken();
                        break;
                }
-               if (!inset->editable()) {
-                       LYXERR0("Inset found on cursor stack is not editable.");
+               if ((inset->inMathed() && !inset->isActive())
+                   || (!inset->inMathed() && !inset->editable())) {
+                       LYXERR0("Inset found on cursor stack is not active.");
                        fixIfBroken();
                        break;
                }