On 04 Mar 2015, at 6:49 , Victor Porton <address@hidden> wrote:

 I have theorems of the form B=>C in one section and theorems of the form A=>C in another section. I want to replace them with a single theorem A=>B=>C (an join two sections into one). I am going to do it around hundred times. I see no reasonable way to do it without editing my book in two windows at once. But editing in two windows is seriously broken in 1.99.2.

And you can't do it by copying the document to a second file, and opening two windows for two documents, but copying things only
one way?

What platform are you working on? linux/osx/windows?