osc.lua: add an icon for the miscellaneous menu

Add the generic menu to bar layouts to provide discoverability for the
select menus to users who don't realize you can right click OSC buttons.

There's no space to add it in box layout.

player/lua/osc.lua

@@ -71,6 +71,10 @@ local user_opts = {
 
     -- luacheck: push ignore
     -- luacheck: max line length
+    menu_mbtn_left_command = "script-binding select/menu; script-message-to osc osc-hide",
+    menu_mbtn_mid_command = "",
+    menu_mbtn_right_command = "",
+
     playlist_prev_mbtn_left_command = "playlist-prev",
     playlist_prev_mbtn_mid_command = "show-text ${playlist} 3000",
     playlist_prev_mbtn_right_command = "script-binding select/select-playlist; script-message-to osc osc-hide",
@@ -134,6 +138,7 @@ local icon_font = "mpv-osd-symbols"
 -- for i = 1, #glyph do output = output .. '\\' .. string.byte(glyph, i) end
 -- print(output)
 local icons = {
+    menu = "\238\132\130",           -- E102
     prev = "\238\132\144",           -- E110
     next = "\238\132\129",           -- E101
     pause = "\238\128\130",          -- E002
@@ -1603,9 +1608,14 @@ local function bar_layout(direction, slim)
     lo.alpha[1] = user_opts.boxalpha
 
 
+    -- Menu
+    geo = { x = osc_geo.x + padX + 4, y = line1, an = 4, w = 18, h = 18 - padY }
+    lo = add_layout("menu")
+    lo.geometry = geo
+    lo.style = osc_styles.topButtonsBar
+
     -- Playlist prev/next
-    geo = { x = osc_geo.x + padX, y = line1,
-            an = 4, w = 18, h = 18 - padY }
+    geo = { x = geo.x + geo.w + padX, y = geo.y, an = geo.an, w = geo.w, h = geo.h }
     lo = add_layout("playlist_prev")
     lo.geometry = geo
     lo.style = osc_styles.topButtonsBar
@@ -1848,6 +1858,11 @@ local function osc_init()
     end
     bind_mouse_buttons("title")
 
+    -- menu
+    ne = new_element("menu", "button")
+    ne.content = icons.menu
+    bind_mouse_buttons("menu")
+
     -- playlist buttons
 
     -- prev