So actually all I'm asking is allow the user to turn on a column where they can select a symbol - for consistency I would allow only one symbol e.g. I pick a circle, you a square, and a third a triangle etc - and assign it a colour based on some criteria and display that.
What the meanings of those colours are; how many of them you use; or how to assign them is up to the user. These "Tags" can either be rules based (e.g. pixels) or manually assigned via a tagging menu or descript.ion method.
So I want to be able to tag "cat pictures" with a pink dot and you want to have a dark blue square for "mp3s over an hour in length" or manually be able to tag "good quality" vs "low quality"
If it was just text you could probably already do it now with a (scripting) plugin, but that information would have the same colour as the filename (set by define colours by filetype). I don't see another way to introduce a "colour label" into the file panel in a reasonable manner - I'm fairly certain allow "per column text colour" is never going to happen either as it would look as horrible as different fonts. A symbol just might be acceptable.
But it is just a suggestion, other ideas of how to get more visual cues into a file panel are allowed of course
Edit: proof of concept, "tags" stored in a file called "tags.ion" and use a AutoHotkey script and WinScriptsAdv (wdx) to populate the "tags" column with "o" and "x" (just to illustrate) https://github.com/hi5/_resources/blob/master/tc-tags.png
As you can't move the name/ext columns (it seems) the tags can't be placed as suggested earlier and of course no colour and no unicode chars that I could get to display in the column (hence o x as "proof")