Two good Stack Exchange answers from Raphael at Digital Pianism covering how to add a custom icon to your Magento Admin Menu Items.
In short – these menu items use a custom font character, defined in svg file that’s (somehow? via LESS CSS?) converted to an embedded OpenType font. This custom font uses the Private Use Area of Unicode to define a custom code point for the new font character. The <li/>
of each menu item gets its own CSS class, and that classes uses the content
style to set the unicode character as the <li/>
’s content.
So, high level, if you want to add your own custom icon you need to
- Use a program like IcoMoon to generate an SVG version of the font-character
- Create four other font formats (maybe via generation, maybe on your own
- Add a LESS CSS rule to include your custom font
- Add a LESS CSS rule to add the Unicode character as a
content
character
I will not be surprised if many extension developers skip all this and end up jamming an image in there instead.
Also, tell me again how being a developer is blue collar/HVAC type work?