EDIT:
Sorry, I did not read your post to the end ...
No, I unfortunately do not know how to extract those textures
But why don't you just let the chat fade out to 10% or 0%? This is a standard ESO setting.
Together with my addon FCOChatTabBrain you can make the 3 icons + other icons face out too.
it gives you possibility to control the chat by keybindings as well + many other nice options.
And the addon pChat, which is a really handy chat enhancement/changer, you can make the text of the chat window fade in again so only the text is shown and everything else is hidden until you hover it.
It gives you also some other features like timstamps, copy messages to clipboard, copy chat settings (chat tabs, etc.) from char 1 to char 2.
My old message was:
Oh, well :-) I don't use the fill line as an addon is telling me % value of the "fill state".
I like it this way because there are some ultimate skills, that get more power with higher % values (like 1000% maximum, instead of 100% where the fill line ends).
I think you cannot access the art folder or any other folders of the game.
But you are able to put some .dds texture files in your addon#s folder, or better a subfolder.
Check the addon "Destinations" or "Inventory Grid View" e.g.
They got an "assets" folder containing texture .dds files.
In your addon source code you are able to load the filenames into an array/table, like Inventory grid view does:
Lua Code:
local TEXTURES = {
["Classic"] = {
BACKGROUND = "InventoryGridView/assets/griditem_background.dds", --set to black?
OUTLINE = "InventoryGridView/assets/griditem_outline.dds",
HOVER = "InventoryGridView/assets/griditem_hover.dds",
TOGGLE = "InventoryGridView/assets/grid_view_toggle_button.dds"
},
You just need to put the correct addon folder name (yours would be "NoActionbarBorders" then) and the folder + .dds filename.
This way you could replace the textures, maybe.