osc: fade out if paused and mouse position is outside of OSC

This broke with the recent changes since tick() is not called regularly
anymore in paused mode. Add an explicit timer for this.

player/lua/osc.lua

@@ -128,6 +128,7 @@ local state = {
     fullscreen = false,
     tick_timer = nil,
     tick_last_time = 0,                     -- when the last tick() was run
+    hide_timer = nil,
     cache_state = nil,
     idle = false,
     enabled = true,
@@ -2297,11 +2298,23 @@ function render()
     end
 
     -- autohide
-    if not (state.showtime == nil) and (user_opts.hidetimeout >= 0)
-        and (state.showtime + (user_opts.hidetimeout/1000) < now)
-        and (state.active_element == nil) and not (mouse_over_osc) then
-
-        hide_osc()
+    if not (state.showtime == nil) and (user_opts.hidetimeout >= 0) then
+        local timeout = state.showtime + (user_opts.hidetimeout/1000) - now
+        if timeout <= 0 then
+            if (state.active_element == nil) and not (mouse_over_osc) then
+                hide_osc()
+            end
+        else
+            -- the timer is only used to recheck the state and to possibly run
+            -- the code below again
+            if not state.hide_timer then
+                state.hide_timer = mp.add_timeout(0, tick)
+            end
+            state.hide_timer.timeout = timeout
+            -- re-arm
+            state.hide_timer:kill()
+            state.hide_timer:resume()
+        end
     end