titlebars: Use the request system rather than 'manage'.

As awesomerc.lua "manage" section is executed after the rules, using
a 'geometry' or 'placement' property in the rules was broken.

awesomerc.lua

@@ -458,6 +458,11 @@ awful.rules.rules = {
         }
       }, properties = { floating = true }},
 
+    -- Add titlebars to normal clients and dialogs
+    { rule_any = {type = { "normal", "dialog" }
+      }, properties = { titlebars_enabled = true }
+    },
+
     -- Set Firefox to always map on the tag named "2" on screen 1.
     -- { rule = { class = "Firefox" },
     --   properties = { screen = 1, tag = "2" } },
@@ -481,48 +486,48 @@ client.connect_signal("manage", function (c)
         -- Prevent clients from being unreachable after screen count changes.
         awful.placement.no_offscreen(c)
     end
+end)
 
-    local titlebars_enabled = true
-    if titlebars_enabled and (c.type == "normal" or c.type == "dialog") then
-        -- buttons for the titlebar
-        local buttons = awful.util.table.join(
-            awful.button({ }, 1, function()
-                client.focus = c
-                c:raise()
-                awful.mouse.client.move(c)
-            end),
-            awful.button({ }, 3, function()
-                client.focus = c
-                c:raise()
-                awful.mouse.client.resize(c)
-            end)
-        )
+-- Add a titlebar if titlebars_enabled is set to true in the rules.
+client.connect_signal("request::titlebars", function(c)
+    -- buttons for the titlebar
+    local buttons = awful.util.table.join(
+        awful.button({ }, 1, function()
+            client.focus = c
+            c:raise()
+            awful.mouse.client.move(c)
+        end),
+        awful.button({ }, 3, function()
+            client.focus = c
+            c:raise()
+            awful.mouse.client.resize(c)
+        end)
+    )
 
-        awful.titlebar(c) : setup {
-            { -- Left
-                awful.titlebar.widget.iconwidget(c),
-                buttons = buttons,
-                layout  = wibox.layout.fixed.horizontal
+    awful.titlebar(c) : setup {
+        { -- Left
+            awful.titlebar.widget.iconwidget(c),
+            buttons = buttons,
+            layout  = wibox.layout.fixed.horizontal
+        },
+        { -- Middle
+            { -- Title
+                align  = "center",
+                widget = awful.titlebar.widget.titlewidget(c)
             },
-            { -- Middle
-                { -- Title
-                    align  = "center",
-                    widget = awful.titlebar.widget.titlewidget(c)
-                },
-                buttons = buttons,
-                layout  = wibox.layout.flex.horizontal
-            },
-            { -- Right
-                awful.titlebar.widget.floatingbutton (c),
-                awful.titlebar.widget.maximizedbutton(c),
-                awful.titlebar.widget.stickybutton   (c),
-                awful.titlebar.widget.ontopbutton    (c),
-                awful.titlebar.widget.closebutton    (c),
-                layout = wibox.layout.fixed.horizontal()
-            },
-            layout = wibox.layout.align.horizontal
-        }
-    end
+            buttons = buttons,
+            layout  = wibox.layout.flex.horizontal
+        },
+        { -- Right
+            awful.titlebar.widget.floatingbutton (c),
+            awful.titlebar.widget.maximizedbutton(c),
+            awful.titlebar.widget.stickybutton   (c),
+            awful.titlebar.widget.ontopbutton    (c),
+            awful.titlebar.widget.closebutton    (c),
+            layout = wibox.layout.fixed.horizontal()
+        },
+        layout = wibox.layout.align.horizontal
+    }
 end)
 
 -- Enable sloppy focus

lib/awful/client.lua

@@ -1122,6 +1122,12 @@ capi.client.add_signal("property::floating")
 
 capi.client.add_signal("property::dockable")
 
+--- Emited when a client need to get a titlebar.
+-- @signal request::titlebars
+-- @tparam[opt=nil] string content The context (like "rules")
+-- @tparam[opt=nil] table hints Some hints.
+capi.client.add_signal("request::titlebars")
+
 --- The client marked signal (deprecated).
 -- @signal .marked
 capi.client.add_signal("marked")

lib/awful/rules.lua

@@ -361,6 +361,10 @@ end
 -- @tab props Properties to apply.
 -- @tab[opt] callbacks Callbacks to apply.
 function rules.execute(c, props, callbacks)
+    -- This has to be done first, as it will impact geometry related props.
+    if props.titlebars_enabled then
+        c:emit_signal("request::titlebars", "rules", {properties=props})
+    end
 
     -- Before requesting a tag, make sure the screen is right
     if props.screen then