To view the list of file types recognized by WebStorm, in the Settings/Preferences dialog Ctrl+Alt+S, go to . If a file in your project is marked with the icon, it indicates that WebStorm can't recognize it. In this case, you can register and configure a new file type.
Icons in tool windows and structure views
Function in Dart
Anonymous bookmark – a check sign bookmark. Bookmarks are used for quick navigation within a file or across the entire project.
Lettered mnemonic bookmark – a letter in the interval from A to Z.
Numbered mnemonic bookmark – a number in the interval from 0 to 9.
Icons in the gutter
A method that overrides a method in the superclass
An interface or its method that has implementations
A method that implements an interface method
Run or debug test
The test passed successfully
The test failed, rerun