bindings: change the way we jump to the urgent window

Pull the first window with urgent flag in the current workspace if not
displayed. If displayed, just raise it. If no urgent window, push back
the previous urgent window to its original tag.

rc/bindings.lua

@@ -3,6 +3,7 @@ config.mouse = {}
 local volume = loadrc("volume", "vbe/volume")
 local brightness = loadrc("brightness", "vbe/brightness")
 local keydoc = loadrc("keydoc", "vbe/keydoc")
+local sharetags = loadrc("sharetags", "vbe/sharetags")
 
 local function screenshot(client)
    if not client then
@@ -15,6 +16,56 @@ local function screenshot(client)
    awful.util.spawn("import -window " .. client .. " " .. path, false)
 end
 
+-- Pull the first window with urgent flag in the current workspace if
+-- not displayed. If displayed, just raise it. If no urgent window,
+-- push back the previous urgent window to its original tag
+local urgent_undo_stack = {}
+local function pull_urgent()
+   local cl = awful.client.urgent.get()
+   local s = client.focus and client.focus.screen or mouse.screen
+   if cl then
+      -- So, we have a client.
+      if not cl:isvisible() then
+	 -- But it is not visible. So we will add it to the current
+	 -- tag of the current screen.
+	 local t = awful.tag.selected(s)
+	 if not t then
+	    return awful.client.urgent.jumpto()
+	 end
+	 -- Before adding the tag to the client, we should ensure it
+	 -- is on the same screen.
+	 if s ~= cl.screen then
+	    sharetags.tag_move(cl:tags()[1], s)
+	 end
+	 -- Add our tag to the client
+	 urgent_undo_stack[#urgent_undo_stack + 1] = { cl, t }
+	 awful.client.toggletag(t, cl)
+      end
+
+      -- Focus and raise the client
+      if s ~= cl.screen then
+	 mouse.screen = cl.screen
+      end
+      client.focus = cl
+      cl:raise()
+   else
+      -- OK, we need to restore the previously pushed window to its
+      -- original state.
+      while #urgent_undo_stack > 0 do
+	 local cl, t = unpack(table.remove(urgent_undo_stack,
+					   #urgent_undo_stack))
+	 -- We only handle visible clients that are attached to the
+	 -- appropriate tag. Otherwise, the client is discarded (and
+	 -- won't be restored later).
+	 if cl and cl:isvisible() and
+	    awful.util.table.hasitem(cl:tags(), t) then
+	    awful.client.toggletag(t, cl)
+	    return
+	 end
+      end
+   end
+end
+
 config.keys.global = awful.util.table.join(
    keydoc.group("Focus"),
    awful.key({ modkey,           }, "j",
@@ -37,7 +88,7 @@ config.keys.global = awful.util.table.join(
 		end
 	     end,
 	     "Focus previously focused window"),
-   awful.key({ modkey,           }, "u", awful.client.urgent.jumpto,
+   awful.key({ modkey,           }, "u", pull_urgent,
 	    "Jump to urgent-flagged window"),
    awful.key({ modkey, "Control" }, "j", function () awful.screen.focus_relative( 1) end,
 	     "Jump to next screen"),