Tested on AX 2012 R3 and TFS 2013
The code merging window is not popping up as expected in TFS 2013. This is probably caused
by the changes made to the merge tool of TFS 2013 according to this article :
http://blogs.msdn.com/b/bharry/archive/2011/08/31/merge-enhancements-in-tfs-11.aspx
Workaround suggestion:
Install the Visual Studio 2010 Team Exploreron on developers machines (Download link):
http://www.microsoft.com/en-in/download/details.aspx?id=329
After that, merging window is popping up:
