(GameMaker) RGB SPLIT

///NEW VERSION (screen-based):

//Draw GUI:
draw_set_blend_mode_ext(bm_one, bm_inv_src_color);
draw_surface_ext(application_surface, 5, 0, 1, 1, 0, c_red, 1);
draw_surface_ext(application_surface, 0, 0, 1, 1, 0, c_lime, 1);
draw_surface_ext(application_surface, -5, 0, 1, 1, 0, c_blue, 1);
draw_set_blend_mode(bm_normal);

//Begin Step (optional):
if (display_get_gui_width() != surface_get_width(application_surface) || display_get_gui_height() != surface_get_height(application_surface)){
    surface_resize(application_surface, display_get_gui_width(), display_get_gui_height());
}

///OLD VERSION (view-based):

// Create event:
viewSur = surface_create(view_wview[view_current], view_hview[view_current]);
view_surface_id[view_current] = viewSur;

// Begin Step:
if (!surface_exists(viewSur)){
    viewSur = surface_create(view_wview[view_current], view_hview[view_current]);
    view_surface_id[view_current] = viewSur;
}

// Draw GUI:
draw_set_blend_mode(bm_add);
draw_surface_ext(viewSur, 5, 0, hscale, vscale, 0, c_red, 1);
draw_surface_ext(viewSur, 0, 0, hscale, vscale, 0, c_lime, 1);
draw_surface_ext(viewSur, -5, 0, hscale, vscale, 0, c_blue, 1);
draw_set_blend_mode(bm_normal);