It uses "user32.dll" that ships with any version of windows. You just need to copy and past
; User32.decls ; .lib "user32.dll" User32_GetSystemMetrics% (nIndex%) : "GetSystemMetrics"in a .decls file (say "user32.decls") and to put it in your "Blitz3D\userlibs" directory. And then in blitz you can do
Global DesktopWidth = User32_GetSystemMetrics(0) Global DesktopHeight = User32_GetSystemMetrics(1)