Token windows are commonly used in various applications, including:

1. Compilers: Token windows are used to store the tokens generated by the lexical analyzer (tokenizer) during the compilation process. These tokens are then used by the parser to build the abstract syntax tree (AST) of the program.
2. Text editors: Token windows can be used to store the tokens generated by the editor's lexer, allowing for efficient searching, replacing, and formatting of text.
3. Programming languages: Some programming languages, such as Python, use token windows to store the tokens generated by the lexer, which are then used by the parser to build the AST.