Garry's Mod Wiki

system.IsWindowed

  boolean system.IsWindowed()

Description

Returns whether the game is being run in a window or in fullscreen (you can change this by opening the menu, clicking 'Options', then clicking the 'Video' tab, and changing the Display Mode using the dropdown menu):

Returns

1 boolean
Is the game running in a window?

Example

If the game is windowed, then the game window will flash