As the title denotes, the technology currently being researched should only change if a new one is actually selected.  It is far too easy for the user to accidentally change what is being researched just by flipping pages while browsing through the Govern menus.

In the following picture, note that the technology currently being researched is Mining (1):

For some reason, I have made habit of thinking about whether any Spells need to be cast, or any Governing needs to be done, before ending my Turns (2).

Notice the red streak trailing to the right of the City List (3):

While browsing, the user decides to take a look at their Kingdom Report (4).

Then, something gives rise to a curiosity regarding Research (5)(6):

"Was it in the Warfare tree?"(7):

Now, the user hasn't even rolled over any specific technologies, let alone clicked one, but they do decide to go take a look at the unit designer (8):

All Done governing for now (9):

Notice that now the technology currently being researched is Leatherworking, even though the user did not actually select it (10):

Ending a turn with the wrong technology selected is not uncommon, especially since the user had no intention of changing it, and the window that actually displays the current research path is nowhere near the Turn button (11).  This demonstration is complex in order to get the point across, but the problem arises quite frequently just browsing through the different research paths.

I highly recommend that the current research selection only be changed if the Done button is pressed from one of the Research pages; or at least only when a new technology is actually clicked on.

It is small inconsiderations in the user interface like this that tip the fun-frustration scale in the wrong direction.  There are quite a few, and I only hope new players are as enthralled with the actual game mechanics as I am for the scale to be fixed in the fun position.  Picking about issues like this should hint at how wonderful the underlying game truly is.