default config: enhance list of default floating clients

Closes https://github.com/awesomeWM/awesome/pull/329

awesomerc.lua

@@ -423,12 +423,33 @@ awful.rules.rules = {
                      raise = true,
                      keys = clientkeys,
                      buttons = clientbuttons } },
-    { rule = { class = "MPlayer" },
-      properties = { floating = true } },
-    { rule = { class = "pinentry" },
-      properties = { floating = true } },
-    { rule = { class = "gimp" },
-      properties = { floating = true } },
+
+    -- Floating clients.
+    { rule_any = {
+        instance = {
+          "DTA",  -- Firefox addon DownThemAll.
+          "copyq",  -- Includes session name in class.
+        },
+        class = {
+          "Arandr",
+          "Gpick",
+          "Kruler",
+          "MessageWin",  -- kalarm.
+          "Sxiv",
+          "Wpa_gui",
+          "pinentry",
+          "veromix",
+          "xtightvncviewer"},
+
+        name = {
+          "Event Tester",  -- xev.
+        },
+        role = {
+          "AlarmWindow",  -- Thunderbird's calendar.
+          "pop-up",       -- e.g. Google Chrome's (detached) Developer Tools.
+        }
+      }, properties = { floating = true }},
+
     -- Set Firefox to always map on tags number 2 of screen 1.
     -- { rule = { class = "Firefox" },
     --   properties = { tag = tags[1][2] } },