Well, I don't want to implement this. IMO, the effort to implement this would be much higher than the use of it. It would probably cause heavy changes in the included tagmanager code and needs a lot of work to make the current code working with nested tags.
That's ok, I don't use the symbols tab all that much, it would have been nice, but if it's a lot of work, I understand.
We could use a GTK stock icon so the icon would change when changing the global icon theme. But in general these icons are much larger than the current one, so the notebook tabs would become quite larger and people may think of wasting space because of these big icons. The current cross is probably not very nice but it is at least small. Any suggestions are welcome.
I don't actually expect these to be done anyway, they are merely cosmetic and totally unnecessary. I did actually measure the height of tabs in GEdit with stock close icon, height of tabs in Geany with little black cross, and tabs without a close icon, like the Symbols tab on the left dock in Geany.
Both GEdit with stock and Geany with the little black cross were 29 pixels high, and tabs without a close button were 28 pixels high. So it doesn't actually seem to make any difference, although it could maybe on some GTK themes. But it's only cosmetic in the end, so don't worry about it.
Second one, is the new icons added to the Symbols are nice and all, but they don't blend in very well with the rest of my desktop. It would be really nice to see them more Tango-ified.
Yes, it would be nice. But it seems there are no appropriate Tango icons available.
Maybe if I have some spare time one day, and if I feel like it, I will see what I can whip up in Inkscape. If I do, I will post my icons, but don't hold me to that :)