My LaTeX Editor (Kile) is deleting most of my root file "master.tex" with a single mouse click in the wrong area. This is when I aim my mouse poorly to get the cursor at the beginning of a line. It happens ONLY in the master.tex file, not in the input files like Preamble.tex or chapter11.tex or the any of the other tex files. The [!!DON'T!!] click zone is just outside of the Left Margin of the text area and below a triangle that marks the location of \begin{document} If clicked, Everything below suddenly highlights and deletes in a fraction of a second.
See the pictures I highlighted. It affects EVERYTHING in master.tex below the \begin{document} line.
BTW, The master.tex will contain links to everything, including a dozen chapter.tex files. "master.tex" is the root file of the project in Kile. Sometimes I can undo. Other times I can't undo (in which case I close the file without saving)
It must be a useful feature that folks depend on, so I'd like to empower myself with the purpose it's intended to help, or deactivate it somehow.
So, Explain why a click in that zone deletes everything, and the purpose folks use it for (or it a glitch and how do I deactivate it?)
[I'm using Kile 2.1.3 under Kubuntu 14.04.]
BEFORE I CLICK IN THE BLUE ZONE:

AFTER I CLICK IN THE BLUE ZONE:



\beginhas something to do with it. Is it a text "expand/collapse" feature? – jon Jul 02 '15 at 17:33