activate buttons for some time

The active state has 2 uses:
* It gives some visual feedback that a button has been pressed.
  Otherwise, tapping a button gave no feedback that the tap had
  occurred. Particularly on a phone screen where fat-fingering is
  easier, hitting the 'save' button in particular gave no hint that the
  file had actually been saved. Which causes some anxiety.
* It suppresses all mouse taps during the activation time. For example,
  this helps keep tapping say an overflow button from selecting text in
  the editor.

0004-on.update

@@ -1,5 +1,8 @@
 on.update = function(dt)
 	refresh_debug_animations()
+	if Active_button and Active_button.expire <= Current_time then
+		Active_button = nil
+	end
 	if App.mouse_down(1) then
 		update_any_sliders(App.mouse_x(), App.mouse_y())
 	end
@@ -9,4 +12,4 @@ on.update = function(dt)
 		adjust_scrollbar(Current_pane.output_editor_state, App.mouse_y())
 	end
 	if car.update then call_protected(car.update, dt) end
-end
+end

0016-on.mouse_press

@@ -1,4 +1,6 @@
 on.mouse_press = function(x,y, mouse_button)
+	-- some hysteresis right after a button has been pressed
+	if Active_button then return end
 	if mouse_press_consumed_by_any_button_handler(Global_state, x,y, mouse_button) then
 		return
 	end

0124-styled_button

@@ -2,10 +2,20 @@ styled_button = function(name, x, y, onpress1)
 	local w = App.width(name)+10
 	button(Global_state, name, {x=x, y=y, w=w, h=Line_height, bg={r=0.6, g=0.8, b=0.6},
 		icon = function(p)
-			App.color(Normal_color)
+			if Active_button and Active_button.name == name and Active_button.expire > Current_time then
+				App.color(Highlighted_button_color)
+			else
+				App.color(Normal_color)
+			end
 			love.graphics.rectangle('line', p.x,p.y, p.w,p.h, 2,2)
 			love.graphics.print(name, p.x+5,p.y+2)
 		end,
-		onpress1 = onpress1,
+		onpress1 = function()
+			onpress1()
+			Active_button = {
+				name=name,
+				expire=Current_time+0.1,
+			}
+		end,
 	})
-end
+end

0147-Highlighted_button_color

@@ -0,0 +1 @@
+Highlighted_button_color = {r=1, g=1, b=1}

0148-Active_button

@@ -0,0 +1,3 @@
+Active_button = nil
+-- When a button is pressed:
+--   {name=..., expire=...}