Created attachment 214152 [details]
Screenshot

I observe a strange bug in the message view of evolution. If the mail is an HTML mail and I click somewhere in the mail body, the effect is as if I had selected, by draggin, an area reaching from a few centimeters above the point where I have clicked to the point where I have clicked. The distance seems to be exactly the height of the header lines table, this is confirmed by collapsing the headers and retrying the experiment. It seems for the coordinates of a mouse-down-event, the header table is ignored, but not for the coordinates of a mouse-up-event.

In the attached screenshot, I have clicked on the “e” at the end of the selection. This single-click created the selection.

libgtkhtml 4.2.2, evolution 3.2.2, libgtk 3.4.2 on Debian unstable.