Make IconButton updates regional

Beginning of the quest to make menu refreshes slightly smoother ;).

frontend/ui/widget/iconbutton.lua

@@ -2,6 +2,7 @@ local InputContainer = require("ui/widget/container/inputcontainer")
 local ImageWidget = require("ui/widget/imagewidget")
 local GestureRange = require("ui/gesturerange")
 local UIManager = require("ui/uimanager")
+local DEBUG = require("dbg")
 
 --[[
 Button with a big icon image! Designed for touch device
@@ -40,6 +41,11 @@ end
 
 function IconButton:onTapClickButton()
     self.image.invert = true
+    UIManager.update_regions_func = function()
+        DEBUG("update iconbutton region", self[1].dimen)
+        return {self[1].dimen}
+    end
+
     UIManager:setDirty(self.show_parent, "partial")
     -- make sure button reacts before doing callback
     UIManager:scheduleIn(0.1, function()