add Kindle-like dictionary window follow-up

frontend/ui/widget/closebutton.lua

@@ -0,0 +1,45 @@
+local InputContainer = require("ui/widget/container/inputcontainer")
+local FrameContainer = require("ui/widget/container/framecontainer")
+local CenterContainer = require("ui/widget/container/centercontainer")
+local TextWidget = require("ui/widget/textwidget")
+local GestureRange = require("ui/gesturerange")
+local UIManager = require("ui/uimanager")
+local Geom = require("ui/geometry")
+local Font = require("ui/font")
+
+--[[
+a button widget that shows an "×" and handles closing window when tapped
+--]]
+local CloseButton = InputContainer:new{
+	align = "right",
+	window = nil,
+}
+
+function CloseButton:init()
+	local text_widget = TextWidget:new{
+		text = "×",
+		face = Font:getFace("cfont", 32),
+	}
+	self[1] = FrameContainer:new{
+		bordersize = 0,
+		padding = 0,
+		text_widget
+	}
+	
+	self.dimen = text_widget:getSize():copy()
+
+	self.ges_events.Close = {
+		GestureRange:new{
+			ges = "tap",
+			range = self.dimen,
+		},
+		doc = "Tap on close button",
+	}
+end
+
+function CloseButton:onClose()
+	self.window:onClose()
+	return true
+end
+
+return CloseButton