JFD
Kathigitarkh
This is a mod designed to allow modders to add custom Yield Per Turn rates to the Top Panel with an associated Tooltip, without the need for complicated workarounds such as by overwriting the TopPanel.lua file. It will also be used by mod-users to allow that support. This mod is compatible with any mods which edit the TopPanel (including EUI, and Health and Plague), but may have odd interactions with those which already use similar methods to add values to the TopPanel (such as my Armenia civ, which adds a new source of Faith Per Turn. This will be updated asap). These methods should be depreciated into using the one prepared here. In the case of EUI, a special edition of this mod will be necessary to accommodate the differences in Tooltip structure, but this will come later.
Important This version is currently outdated and won't be used for a while. P&P has the latest version.
It should be noted that this mod will be incorporated into my Piety & Prestige mod, as that mod makes more robust changes to the Faith and Culture tooltips.
Download
Mods with support:
JFD's The Kingdom of Hungary
JFD's The Holy Roman Empire
For Users
Download and install the mod as any other.
For Modders
Using this mod is fairly simple. All you need is this file, which will explain the process of adding a new YieldPerTurn + Tooltip to the TopPanel.
Please let me know of any bugs, and if anyone would like me to expand this to allow tooltips to be added to other parts of the TopPanel.
Changelog

Important This version is currently outdated and won't be used for a while. P&P has the latest version.
It should be noted that this mod will be incorporated into my Piety & Prestige mod, as that mod makes more robust changes to the Faith and Culture tooltips.
Download
Mods with support:
JFD's The Kingdom of Hungary
JFD's The Holy Roman Empire
For Users
Download and install the mod as any other.
For Modders
Using this mod is fairly simple. All you need is this file, which will explain the process of adding a new YieldPerTurn + Tooltip to the TopPanel.
Please let me know of any bugs, and if anyone would like me to expand this to allow tooltips to be added to other parts of the TopPanel.
Changelog
6/11: Fixed a bug with the Culture Per Turn display
7/11: Fixed an issue where the playerID wouldn't pass to the string functions.