This was in modding_lua.txt for the past few years. It really needs to be in its own thing.
This also covers the event system.
--GM

font_mini
	Small ASCII font, for most body text.
	
font_large
	Big ASCII font, for headers and stuff.
	
font_digits
	Big numeric font, for HUD counters.

gui_index_mini(i)
	Character lookup helper for the mini font
	
gui_index_digit(i)
	Character lookup helper for the digit font

gui_create_fixwidth_font(image, char_width, char_height, indexing_fn, shadow)
	Creates a new fixed width bitmap font.
		
	compute_unwrapped(x, y, color, string)
		Computes specific glyphs and positions needed from a string, color, and x/y coordinates.
	
	compute_ctab(ctab, x, y)
		Computes specific glyphs and positions from a color table, 
		where each line of the table contains a string "msg" and a color "color",
		and will be positioned underneath the previous line.
		
	compute_wordwrap(width, x, y, color, string)
		Computes specific glyphs and positions from a word-wrapped string, within the width argument.
	
	dimensions(data)
		Get the AABB dimensions of text(l,r,t,b, width, height) given precomputed text data
	
	calc_shadow(color)
		Calculate the shadow strength from the percieved luminance of the font; brighter color = darker shadow
	
	print(x, y, color, string, buffer=nil)
		Print text with topleft at x, y, color c, string str.
		buffer defines where the text is drawn - to the screen or to an offscreen buffer.
		
	print_precomputed(data, offx, offy, buffer=nil)
		Print precomputed text to the given buffer.
	
	print_wrap(wp, x, y, c, str, buffer)
		Print text with minimum-space wordwrapping, pixelwidth wp, topleft at x, y, color c, string str

alarm{time=1, progress=0, active=true, loop=false, preserve_accumulator=true, on_frame=nil, on_trigger=nil}
	Create an alarm with an abstract time value.
	
	time: The target amount of time before the alarm triggers.
	progress: How much time has elapsed(counting from 0 to the target time).
	active: Whether the alarm is presently ticking.
	loop: Whether the alarm loops.
	preserve_accumulator: If the alarm loops, allow the leftover time to carry into the next loop.
	on_frame: A callback run every frame. Recieves the time delta.
	on_trigger: A callback run each time the alarm reaches its target time. Recieves the time delta.
			
gui_create_scene(width, height, shared_rate=1/60)
	Creates a new GUI scene of designated width and height, and a shared update rate in seconds equal to shared_rate.
	
	The GUI system is modelled similarly to the Flash AS3 APIs.
	
	A GUI scene can contain any number of display objects, ordered in a tree structure.
	Each time the GUI is ticked, it processes an event pipeline. An event is a message containing a type and some attached data.
	When an event reaches a display object with a listener of the same type, the listener's callback is called with the event's data.
	
	These events are available:
		GE_DELTA_TIME
			The delta time passed in when listeners are pumped. You can use this to drive tweening over time, for example.
			Callback passes in the dT value.
		GE_SHARED_ALARM
			A tick running at a fixed rate. This is an alternative to delta time for situations where you specifically need a fixed rate,
			for example, an animation that relies on multiplying previous values every step.
			Callback passes in the dT value of the shared alarm timer.
		GE_KEY
			A keypress(up or down) event.
			Callback passes in {key(int), state(bool), modif(int bitmask), uni(int)}
		GE_BUTTON
			A mapped button press(up or down) event. Use this when you expect the button to be reassignable.
			Callback passes in {key(int), button{name(string), desc(string)}, state(bool), modif(int bitmask)}
		GE_MOUSE
			A mouse movement event.
			Callback passes in {x(number), y(number), dx(number), dy(number)}
		GE_MOUSE_BUTTON
			A mouse button press(up or down).
			Callback passes in {button(int), down(bool)}

	
			
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