Why does my icon not appear?

How To Customization
1

Added (copied) the icon setting from openfiles, but it does not appear…
What’s wrong?

2
3

Seems this is a bug, logged it here: https://github.com/Komodo/KomodoEdit/issues/1599

As a workaround you can specify the icon with CSS, eg:

tab[widget="qwinViewbox"] .tab-icon { 
  width: 14px;
  height: 14px;
  visibility: visible;
  background-image: url(...);
}
4

Small note, to show the icon only in icon layout view.
You should specify the icons layout only:

#workspace_left_area[type="icons"] tab[widget="FontAwesomeViewbox"] .tab-icon,
#workspace_right_area[type="icons"] tab[widget="FontAwesomeViewbox"] .tab-icon {
    width: 14px;
    height: 14px;
    visibility: visible;
    background-image: url('...') !important;
}