edgeds_draw_background(background, x, y, index, foreground, tile, scale mode)
|edgeds_draw_background(my_bg, view_xview, view_yview, 0, false, false, 0);|
Assigns the background asset specified in the background parameter to the background slot specified in the index parameter and scales it to fill the 100% of the display with one of three scaling modes.
As of version 1.7.0, five background scaling modes are available in Edge Display Scaler: x and y full scaling (0), x-only scaling (1), y-only scaling (2), fit scaling (3), and proportion scaling (4). Mode 0 scales a background to always fill the screen without stretching, with modes 1 and 2 offering single-axis versions of the same style of scaling. Mode 3 only scales a background downward as necessary to fit small displays while never exceeding 100% scale on larger ones, and Mode 4 scales proportionately to the display whether larger or smaller than the base resolution (without guaranteeing seamless fullscreen).
Because the background is intended to fill the display, it is recommended to set the x and y parameters set to 0 or view_xview and view_yview, where  refers to the desired scaling view, however the background may still be positioned freely regardless of scaling.
By setting the foreground parameter to true the background can appear on top of game assets rather than behind, otherwise false will display the background normally.
Finally, by setting the tile parameter to true the background will repeat in both directions, which can be useful when using manual x and y offsets. Otherwise, false will draw the background only once.
This script can be run in virtually any event.