These editors offer syntax highlighting and integrated compile/run commands for XC=BASIC:

• XC=Edit by Oliver Hermanni, an IDE for XC=BASIC
• Textadept extended with XC=BASIC language module by Csaba Fekete
• Visual Studio Code extended with XC=BASIC language support by Viza (not actively maintained, pre-1.0 syntax only)

All the above run (or at least should compile) on Windows, Linux and Mac.