doc: Improve the `awful` template.

* Support client shape
 * Support titlebar colors
 * Only render clients part of the selected tag(s).

tests/examples/awful/template.lua

@@ -98,10 +98,20 @@ local total_area = wibox.layout {
 }
 
 local function wrap_titlebar(tb, width, height)
+
+    local bg, fg
+
+    if args.honor_titlebar_colors then
+        bg = tb.drawable.background_color or tb.args.bg_normal
+        fg = tb.drawable.foreground_color or tb.args.fg_normal
+    else
+        bg, fg = tb.args.bg_normal, tb.args.fg_normal
+    end
+
     return wibox.widget {
         tb.drawable.widget,
-        bg            = tb.args.bg_normal,
-        fg            = tb.args.fg_normal,
+        bg            = bg,
+        fg            = fg,
         forced_width  = width,
         forced_height = height,
         widget        = wibox.container.background
@@ -160,10 +170,15 @@ local function client_widget(c, col, label)
         border_color    = bc,
         shape_clip      = true,
         border_strategy = "inner",
+        opacity         = c.opacity,
         fg              = beautiful.fg_normal or "#000000",
         bg              = col,
         shape           = function(cr2, w, h)
-            return shape.rounded_rect(cr2, w, h, args.radius or 5)
+            if c.shape then
+                c.shape(cr2, w, h)
+            else
+                return shape.rounded_rect(cr2, w, h, args.radius or 5)
+            end
         end,
 
         forced_width  = geo.width  + 2*bw,
@@ -201,7 +216,14 @@ end
 
 -- Loop each clients geometry history and paint it
 for _, c in ipairs(client.get()) do
-    if not c.minimized then
+
+    local is_displayed = false
+
+    for _, t in pairs(c:tags()) do
+        is_displayed = is_displayed or t.selected
+    end
+
+    if (not c.minimized) and is_displayed then
         local pgeo = nil
         for _, geo in ipairs(c._old_geo) do
             if not geo._hide then