@Thalassicus
Ok, thanks. Followed directions for tuner but no joy, don't know why (yet) and I'll triple-check if'n I did everything correctly and try again. [host OS Ubuntu 12.04 amd64, civ runs via Steam in an XP bottle under Crossover XI, so this may complicate things] Perhaps I could try with 'in-game editor' mod, if it's compatible with the Communtas pack.
I'll try the 'over-rides' thing in vanilla tomorrow.
[At the risk of annoyingly covering old ground, the precise behaviour I see in later game, a dozen to 20 cities (usually in early/mid 1000's, marathon) is that tooltips get to the point where they raise immediately instead of after a short hover time, they persist for what seems to be a set time or a progressibely longer time (or fade slowly, for instance when a unit is deleted or gifted) instead of vanishing instantly when cursor moves. This happens in all places- on map over terrain, features, improvements, units, cities; in city screen- on left and right panels and in city map; in diplo overview; and even in the title bar of the mini-map, albeit the delay there is smaller.]
Disclaimer: I haven't coded in roughly a decade, and while I've started looking at the various lua and xml bits, I find things all a bit daunting. To those who can, and do this stuff, my thanks.