This function gets the height (in pixels) of the GUI as used in the Draw GUI Event.
NOTE When your application_surface is larger than the display's size (roughly), and you call this function before the current room's initialisation has finished, e.g. in a global script, a room's Creation Code or an instance's Create event, the value returned may not be accurate. For accurate results in such cases, call this in a Draw event.
display_get_gui_height();
Draw GUI Event
var _height = display_get_gui_height();
var _valign = draw_get_valign();
draw_set_valign(fa_bottom);
draw_text(5, _height - 5, "I am drawn in the bottom-left corner of the GUI");
draw_set_valign(_valign);
The above code draws a text in the GUI: it first gets the GUI height using display_get_gui_height and then sets the vertical text alignment to fa_bottom, then draws a line of text using draw_text and finally resets the vertical text alignment to its previous value.