diff --git a/frontend/ui/widget/inputtext.lua b/frontend/ui/widget/inputtext.lua
index 82bcbe6de..54524ce37 100644
--- a/frontend/ui/widget/inputtext.lua
+++ b/frontend/ui/widget/inputtext.lua
@@ -18,7 +18,7 @@ local InputText = InputContainer:new{
     charpos = nil, -- position to insert a new char, or the position of the cursor
     input_type = nil,
     text_type = nil,
-	text_widget = nil, -- Text Widget for cursor movement
+    text_widget = nil, -- Text Widget for cursor movement
 
     width = nil,
     height = nil,
@@ -50,15 +50,15 @@ if Device.isTouchDevice() then
     function InputText:onTapTextBox(arg, ges)
         if self.parent.onSwitchFocus then
             self.parent:onSwitchFocus(self)
-		else
-		    local x = ges.pos.x - self.dimen.x - self.bordersize - self.padding
-		    local y = ges.pos.y - self.dimen.y - self.bordersize - self.padding
-		    if x > 0 and y > 0 then
-		    	self.charpos = self.text_widget:moveCursor(x, y)
-		    	UIManager:setDirty(self.parent, function()
-		    		return "ui", self[1].dimen
-		    	end)
-		    end
+        else
+            local x = ges.pos.x - self.dimen.x - self.bordersize - self.padding
+            local y = ges.pos.y - self.dimen.y - self.bordersize - self.padding
+            if x > 0 and y > 0 then
+                self.charpos = self.text_widget:moveCursor(x, y)
+                UIManager:setDirty(self.parent, function()
+                    return "ui", self[1].dimen
+                end)
+            end
         end
     end
 else
@@ -74,10 +74,10 @@ end
 
 function InputText:initTextBox(text)
     self.text = text
-	util.splitToChars(text, self.charlist)
-	if self.charpos == nil then
-		self.charpos = #self.charlist + 1
-	end
+    util.splitToChars(text, self.charlist)
+    if self.charpos == nil then
+        self.charpos = #self.charlist + 1
+    end
     local fgcolor = Blitbuffer.gray(self.text == "" and 0.5 or 1.0)
 
     local show_text = self.text
@@ -88,9 +88,9 @@ function InputText:initTextBox(text)
     if self.scroll then
         self.text_widget = ScrollTextWidget:new{
             text = show_text,
-			charlist = self.charlist,
-			charpos = self.charpos,
-			editable = true,
+            charlist = self.charlist,
+            charpos = self.charpos,
+            editable = true,
             face = self.face,
             fgcolor = fgcolor,
             width = self.width,
@@ -99,9 +99,9 @@ function InputText:initTextBox(text)
     else
         self.text_widget = TextBoxWidget:new{
             text = show_text,
-			charlist = self.charlist,
-			charpos = self.charpos,
-			editable = true,
+            charlist = self.charlist,
+            charpos = self.charpos,
+            editable = true,
             face = self.face,
             fgcolor = fgcolor,
             width = self.width,
diff --git a/frontend/ui/widget/scrolltextwidget.lua b/frontend/ui/widget/scrolltextwidget.lua
index 9039c5a33..2d5735443 100644
--- a/frontend/ui/widget/scrolltextwidget.lua
+++ b/frontend/ui/widget/scrolltextwidget.lua
@@ -16,9 +16,9 @@ Text widget with vertical scroll bar
 --]]
 local ScrollTextWidget = InputContainer:new{
     text = nil,
-	charlist = nil,
-	charpos = nil,
-	editable = false,
+    charlist = nil,
+    charpos = nil,
+    editable = false,
     face = nil,
     fgcolor = Blitbuffer.COLOR_BLACK,
     width = 400,
@@ -31,9 +31,9 @@ local ScrollTextWidget = InputContainer:new{
 function ScrollTextWidget:init()
     self.text_widget = TextBoxWidget:new{
         text = self.text,
-		charlist = self.charlist,
-		charpos = self.charpos,
-		editable = self.editable,
+        charlist = self.charlist,
+        charpos = self.charpos,
+        editable = self.editable,
         face = self.face,
         fgcolor = self.fgcolor,
         width = self.width - self.scroll_bar_width - self.text_scroll_span,
@@ -76,10 +76,10 @@ function ScrollTextWidget:scrollText(direction)
     if direction == 0 then return end
     if direction > 0 then
         low, high = self.text_widget:scrollDown()
-		self.v_scroll_bar:set(low, high)
+        self.v_scroll_bar:set(low, high)
     else
         low, high = self.text_widget:scrollUp()
-		self.v_scroll_bar:set(low, high)
+        self.v_scroll_bar:set(low, high)
     end
     UIManager:setDirty(self.dialog, function()
         return "partial", self.dimen
diff --git a/frontend/ui/widget/textboxwidget.lua b/frontend/ui/widget/textboxwidget.lua
index 1dc095123..b717865f1 100644
--- a/frontend/ui/widget/textboxwidget.lua
+++ b/frontend/ui/widget/textboxwidget.lua
@@ -12,12 +12,12 @@ A TextWidget that handles long text wrapping
 --]]
 local TextBoxWidget = Widget:new{
     text = nil,
-	charlist = nil,
-	charpos = nil,
-	char_width_list = nil, -- list of widths of the chars in `charlist`.
+    charlist = nil,
+    charpos = nil,
+    char_width_list = nil, -- list of widths of the chars in `charlist`.
     vertical_string_list = nil,
-	editable = false, -- Editable flag for whether drawing the cursor or not.
-	cursor_line = nil, -- LineWidget to draw the vertical cursor.
+    editable = false, -- Editable flag for whether drawing the cursor or not.
+    cursor_line = nil, -- LineWidget to draw the vertical cursor.
     face = nil,
     bold = nil,
     line_height = 0.3, -- in em
@@ -29,127 +29,127 @@ local TextBoxWidget = Widget:new{
 }
 
 function TextBoxWidget:init()
-	local line_height = (1 + self.line_height) * self.face.size
-	local font_height = self.face.size
-	self.cursor_line = LineWidget:new{
+    local line_height = (1 + self.line_height) * self.face.size
+    local font_height = self.face.size
+    self.cursor_line = LineWidget:new{
         dimen = Geom:new{
             w = Screen:scaleBySize(1),
             h = line_height,
         }
     }
-	self:_evalCharWidthList()
-	self:_splitCharWidthList()
-	if self.height == nil then
-		self:_renderText(1, #self.vertical_string_list)
-	else
-		self:_renderText(1, self:getVisLineCount())
-	end
-	if self.editable then
-		x, y = self:_findCharPos()
-		self.cursor_line:paintTo(self._bb, x, y)
-	end
-	self.dimen = Geom:new(self:getSize())
+    self:_evalCharWidthList()
+    self:_splitCharWidthList()
+    if self.height == nil then
+        self:_renderText(1, #self.vertical_string_list)
+    else
+        self:_renderText(1, self:getVisLineCount())
+    end
+    if self.editable then
+        x, y = self:_findCharPos()
+        self.cursor_line:paintTo(self._bb, x, y)
+    end
+    self.dimen = Geom:new(self:getSize())
 end
 
 -- Return whether the text widget is editable.
 function TextBoxWidget:isEditable()
-	return self.editable
+    return self.editable
 end
 
 -- Evaluate the width of each char in `self.charlist`.
 function TextBoxWidget:_evalCharWidthList()
-	if self.charlist == nil then
-		self.charlist = {}
-		util.splitToChars(self.text, self.charlist)
-		self.charpos = #self.charlist + 1
-	end
-	self.char_width_list = {}
-	for _, v in ipairs(self.charlist) do
-		w = RenderText:sizeUtf8Text(0, Screen:getWidth(), self.face, v, true, self.bold).x
-		table.insert(self.char_width_list, {char = v, width = w})
-	end
+    if self.charlist == nil then
+        self.charlist = {}
+        util.splitToChars(self.text, self.charlist)
+        self.charpos = #self.charlist + 1
+    end
+    self.char_width_list = {}
+    for _, v in ipairs(self.charlist) do
+        w = RenderText:sizeUtf8Text(0, Screen:getWidth(), self.face, v, true, self.bold).x
+        table.insert(self.char_width_list, {char = v, width = w})
+    end
 end
 
 -- Split the text into logical lines to fit into the text box.
 function TextBoxWidget:_splitCharWidthList()
-	self.vertical_string_list = {}
-	self.vertical_string_list[1] = {text = "Demo hint", offset = 1, width = 0} -- hint for empty string
+    self.vertical_string_list = {}
+    self.vertical_string_list[1] = {text = "Demo hint", offset = 1, width = 0} -- hint for empty string
 
-	local idx = 1
-	local offset = 1
+    local idx = 1
+    local offset = 1
     local cur_line_width = 0
-	local cur_line_text = nil
-	local size = #self.char_width_list
-	local ln = 1
-	while idx <= size do
-		offset = idx
-		-- Appending chars until the accumulated width exceeds `self.width`,
-		-- or a newline occurs, or no more chars to consume.
-		cur_line_width = 0
-		local hard_newline = false
-		cur_line_text = nil
-		while idx <= size do
-			if self.char_width_list[idx].char == "\n" then
-				hard_newline = true
-				break
-			end
-			cur_line_width = cur_line_width + self.char_width_list[idx].width
-			if cur_line_width > self.width then break else idx = idx + 1 end
-		end
-		if cur_line_width <= self.width then -- a hard newline or end of string
-			cur_line_text = table.concat(self.charlist, "", offset, idx - 1)
-		else
-			-- Backtrack the string until the length fit into one line.
-			local c = self.char_width_list[idx].char
-			if util.isSplitable(c) then
-				cur_line_text = table.concat(self.charlist, "", offset, idx - 1)
-				cur_line_width = cur_line_width - self.char_width_list[idx].width
-			else
-				local adjusted_idx = idx
-				local adjusted_width = cur_line_width
-				repeat
-					adjusted_width = adjusted_width - self.char_width_list[adjusted_idx].width
-					adjusted_idx = adjusted_idx - 1
-					c = self.char_width_list[adjusted_idx].char
-				until adjusted_idx > offset and util.isSplitable(c)
-				if adjusted_idx == offset then -- a very long english word ocuppying more than one line
-					cur_line_text = table.concat(self.charlist, "", offset, idx - 1)
-					cur_line_width = cur_line_width - self.char_width_list[idx].width
-				else
-					cur_line_text = table.concat(self.charlist, "", offset, adjusted_idx)
-					cur_line_width = adjusted_line_width
-					idx = adjusted_idx + 1
-				end
-			end -- endif util.isSplitable(c)
-		end -- endif cur_line_width > self.width
-		self.vertical_string_list[ln] = {text = cur_line_text, offset = offset, width = cur_line_width}
-		if hard_newline then
-			idx = idx + 1
-			self.vertical_string_list[ln + 1] = {text = "", offset = idx, width = 0}
-		end
-		ln = ln + 1
-		-- Make sure `idx` point to the next char to be processed in the next loop.
-	end
+    local cur_line_text = nil
+    local size = #self.char_width_list
+    local ln = 1
+    while idx <= size do
+        offset = idx
+        -- Appending chars until the accumulated width exceeds `self.width`,
+        -- or a newline occurs, or no more chars to consume.
+        cur_line_width = 0
+        local hard_newline = false
+        cur_line_text = nil
+        while idx <= size do
+            if self.char_width_list[idx].char == "\n" then
+                hard_newline = true
+                break
+            end
+            cur_line_width = cur_line_width + self.char_width_list[idx].width
+            if cur_line_width > self.width then break else idx = idx + 1 end
+        end
+        if cur_line_width <= self.width then -- a hard newline or end of string
+            cur_line_text = table.concat(self.charlist, "", offset, idx - 1)
+        else
+            -- Backtrack the string until the length fit into one line.
+            local c = self.char_width_list[idx].char
+            if util.isSplitable(c) then
+                cur_line_text = table.concat(self.charlist, "", offset, idx - 1)
+                cur_line_width = cur_line_width - self.char_width_list[idx].width
+            else
+                local adjusted_idx = idx
+                local adjusted_width = cur_line_width
+                repeat
+                    adjusted_width = adjusted_width - self.char_width_list[adjusted_idx].width
+                    adjusted_idx = adjusted_idx - 1
+                    c = self.char_width_list[adjusted_idx].char
+                until adjusted_idx > offset and util.isSplitable(c)
+                if adjusted_idx == offset then -- a very long english word ocuppying more than one line
+                    cur_line_text = table.concat(self.charlist, "", offset, idx - 1)
+                    cur_line_width = cur_line_width - self.char_width_list[idx].width
+                else
+                    cur_line_text = table.concat(self.charlist, "", offset, adjusted_idx)
+                    cur_line_width = adjusted_line_width
+                    idx = adjusted_idx + 1
+                end
+            end -- endif util.isSplitable(c)
+        end -- endif cur_line_width > self.width
+        self.vertical_string_list[ln] = {text = cur_line_text, offset = offset, width = cur_line_width}
+        if hard_newline then
+            idx = idx + 1
+            self.vertical_string_list[ln + 1] = {text = "", offset = idx, width = 0}
+        end
+        ln = ln + 1
+        -- Make sure `idx` point to the next char to be processed in the next loop.
+    end
 end
 
 function TextBoxWidget:_renderText(start_row_idx, end_row_idx)
     local font_height = self.face.size
     local line_height = (1 + self.line_height) * font_height
-	if start_row_idx < 1 then start_row_idx = 1 end
-	if end_row_idx > #self.vertical_string_list then end_row_idx = #self.vertical_string_list end
-	local row_count = end_row_idx == 0 and 1 or end_row_idx - start_row_idx + 1
+    if start_row_idx < 1 then start_row_idx = 1 end
+    if end_row_idx > #self.vertical_string_list then end_row_idx = #self.vertical_string_list end
+    local row_count = end_row_idx == 0 and 1 or end_row_idx - start_row_idx + 1
     local h = line_height *  row_count
     self._bb = Blitbuffer.new(self.width, h)
     self._bb:fill(Blitbuffer.COLOR_WHITE)
-	local y = font_height
-	for i = start_row_idx, end_row_idx do
-		local line = self.vertical_string_list[i]
-		local pen_x = self.alignment == "center" and (self.width - line.width)/2 or 0
-			--@TODO Don't use kerning for monospaced fonts.    (houqp)
-			-- refert to cb25029dddc42693cc7aaefbe47e9bd3b7e1a750 in master tree
-		RenderText:renderUtf8Text(self._bb, pen_x, y, self.face, line.text, true, self.bold, self.fgcolor)
-		y = y + line_height
-	end
+    local y = font_height
+    for i = start_row_idx, end_row_idx do
+        local line = self.vertical_string_list[i]
+        local pen_x = self.alignment == "center" and (self.width - line.width)/2 or 0
+            --@TODO Don't use kerning for monospaced fonts.    (houqp)
+            -- refert to cb25029dddc42693cc7aaefbe47e9bd3b7e1a750 in master tree
+        RenderText:renderUtf8Text(self._bb, pen_x, y, self.face, line.text, true, self.bold, self.fgcolor)
+        y = y + line_height
+    end
 --    -- if text is shorter than one line, shrink to text's width
 --    if #v_list == 1 then
 --        self.width = pen_x
@@ -159,50 +159,50 @@ end
 -- Return the position of the cursor corresponding to `self.charpos`,
 -- Be aware of virtual line number of the scorllTextWidget.
 function TextBoxWidget:_findCharPos()
-	-- Find the line number.
-	local ln = self.height == nil and 1 or self.virtual_line_num
-	while ln + 1 <= #self.vertical_string_list do
-		if self.vertical_string_list[ln + 1].offset > self.charpos then break else ln = ln + 1 end
-	end
-	-- Find the offset at the current line.
-	local x = 0
-	local offset = self.vertical_string_list[ln].offset
-	while offset < self.charpos do
-		x = x + self.char_width_list[offset].width
-		offset = offset + 1
-	end
-	local line_height = (1 + self.line_height) * self.face.size
-	return x + 1, (ln - 1) * line_height -- offset `x` by 1 to avoid overlap
+    -- Find the line number.
+    local ln = self.height == nil and 1 or self.virtual_line_num
+    while ln + 1 <= #self.vertical_string_list do
+        if self.vertical_string_list[ln + 1].offset > self.charpos then break else ln = ln + 1 end
+    end
+    -- Find the offset at the current line.
+    local x = 0
+    local offset = self.vertical_string_list[ln].offset
+    while offset < self.charpos do
+        x = x + self.char_width_list[offset].width
+        offset = offset + 1
+    end
+    local line_height = (1 + self.line_height) * self.face.size
+    return x + 1, (ln - 1) * line_height -- offset `x` by 1 to avoid overlap
 end
 
 -- Click event: Move the cursor to a new location with (x, y), in pixels.
 -- Be aware of virtual line number of the scorllTextWidget.
 function TextBoxWidget:moveCursor(x, y)
-	local w = 0
-	local h = 0
-	local line_height = (1 + self.line_height) * self.face.size
-	local ln = self.height == nil and 1 or self.virtual_line_num
-	ln = ln + math.ceil(y / line_height) - 1
-	if ln > #self.vertical_string_list then
-		ln = #self.vertical_string_list
-		x = self.width
-	end
-	local offset = self.vertical_string_list[ln].offset
-	local idx = ln == #self.vertical_string_list and #self.char_width_list or self.vertical_string_list[ln + 1].offset - 1
-	while offset <= idx do
-		w = w + self.char_width_list[offset].width
-		if w > x then break else offset = offset + 1 end
-	end
-	if w > x then
-		local w_prev = w - self.char_width_list[offset].width
-		if x - w_prev < w - x then -- the previous one is more closer
-			w = w_prev
-		end
-	end
-	self:free()
-	self:_renderText(1, #self.vertical_string_list)
-	self.cursor_line:paintTo(self._bb, w + 1, (ln - self.virtual_line_num) * line_height)
-	return offset
+    local w = 0
+    local h = 0
+    local line_height = (1 + self.line_height) * self.face.size
+    local ln = self.height == nil and 1 or self.virtual_line_num
+    ln = ln + math.ceil(y / line_height) - 1
+    if ln > #self.vertical_string_list then
+        ln = #self.vertical_string_list
+        x = self.width
+    end
+    local offset = self.vertical_string_list[ln].offset
+    local idx = ln == #self.vertical_string_list and #self.char_width_list or self.vertical_string_list[ln + 1].offset - 1
+    while offset <= idx do
+        w = w + self.char_width_list[offset].width
+        if w > x then break else offset = offset + 1 end
+    end
+    if w > x then
+        local w_prev = w - self.char_width_list[offset].width
+        if x - w_prev < w - x then -- the previous one is more closer
+            w = w_prev
+        end
+    end
+    self:free()
+    self:_renderText(1, #self.vertical_string_list)
+    self.cursor_line:paintTo(self._bb, w + 1, (ln - self.virtual_line_num) * line_height)
+    return offset
 end
 
 function TextBoxWidget:getVisLineCount()
@@ -211,34 +211,34 @@ function TextBoxWidget:getVisLineCount()
 end
 
 function TextBoxWidget:getAllLineCount()
-	return #self.vertical_string_list
+    return #self.vertical_string_list
 end
 
 
 -- TODO: modify `charpos` so that it can render the cursor
 function TextBoxWidget:scrollDown()
-	local visible_line_count = self:getVisLineCount()
-	if self.virtual_line_num + visible_line_count <= #self.vertical_string_list then
-		self:free()
-		self.virtual_line_num = self.virtual_line_num + visible_line_count
-		self:_renderText(self.virtual_line_num, self.virtual_line_num + visible_line_count - 1)
-	end
-	return (self.virtual_line_num - 1) / #self.vertical_string_list, (self.virtual_line_num - 1 + visible_line_count) / #self.vertical_string_list 
+    local visible_line_count = self:getVisLineCount()
+    if self.virtual_line_num + visible_line_count <= #self.vertical_string_list then
+        self:free()
+        self.virtual_line_num = self.virtual_line_num + visible_line_count
+        self:_renderText(self.virtual_line_num, self.virtual_line_num + visible_line_count - 1)
+    end
+    return (self.virtual_line_num - 1) / #self.vertical_string_list, (self.virtual_line_num - 1 + visible_line_count) / #self.vertical_string_list 
 end
 
 -- TODO: modify `charpos` so that it can render the cursor
 function TextBoxWidget:scrollUp()
-	local visible_line_count = self:getVisLineCount()
-	if self.virtual_line_num > 1 then
-		self:free()
-		if self.virtual_line_num <= visible_line_count then
-			self.virtual_line_num = 1
-		else
-			self.virtual_line_num = self.virtual_line_num - visible_line_count
-		end
-		self:_renderText(self.virtual_line_num, self.virtual_line_num + visible_line_count - 1)
-	end
-	return (self.virtual_line_num - 1) / #self.vertical_string_list, (self.virtual_line_num - 1 + visible_line_count) / #self.vertical_string_list 
+    local visible_line_count = self:getVisLineCount()
+    if self.virtual_line_num > 1 then
+        self:free()
+        if self.virtual_line_num <= visible_line_count then
+            self.virtual_line_num = 1
+        else
+            self.virtual_line_num = self.virtual_line_num - visible_line_count
+        end
+        self:_renderText(self.virtual_line_num, self.virtual_line_num + visible_line_count - 1)
+    end
+    return (self.virtual_line_num - 1) / #self.vertical_string_list, (self.virtual_line_num - 1 + visible_line_count) / #self.vertical_string_list 
 end
 
 function TextBoxWidget:getSize()
diff --git a/frontend/util.lua b/frontend/util.lua
index 837cb980f..fbb533793 100644
--- a/frontend/util.lua
+++ b/frontend/util.lua
@@ -101,11 +101,11 @@ end
 -- @text: the string to be splitted.
 -- @tab: the table to store the chars sequentially, must not be nil.
 function util.splitToChars(text, tab)
-	if text == nil then return end
+    if text == nil then return end
     -- clear
     for k, v in pairs(tab) do
-		tab[k] = nil
-	end
+        tab[k] = nil
+    end
     local prevcharcode, charcode = 0
     for uchar in string.gfind(text, "([%z\1-\127\194-\244][\128-\191]*)") do
         charcode = BaseUtil.utf8charcode(uchar)
@@ -118,7 +118,7 @@ end
 
 -- Test whether a string could be separated by a char for multi-line rendering
 function util.isSplitable(c)
-	return #c > 1 or c == " " or string.match(c, "%p") ~= nil
+    return #c > 1 or c == " " or string.match(c, "%p") ~= nil
 end
 
 return util