diff --git a/assets/root/intrologin.py b/assets/root/intrologin.py
index 239d8920..bd1dba42 100644
--- a/assets/root/intrologin.py
+++ b/assets/root/intrologin.py
@@ -325,30 +325,30 @@ class LoginWindow(ui.ScriptWindow):
 
 	def __SaveChannelInfo(self):
 		try:
-			file=open("channel.inf", "w")
-			file.write("%d %d %d" % (self.__GetServerID(), self.__GetChannelID(), self.__GetRegionID()))
+			with open("channel.inf", "w") as file:
+				file.write("%d %d %d" % (self.__GetServerID(), self.__GetChannelID(), self.__GetRegionID()))
 		except:
 			print "LoginWindow.__SaveChannelInfo - SaveError"
 
 	def __LoadChannelInfo(self):
 		try:
-			file=open("channel.inf")
-			lines=file.readlines()
-			
-			if len(lines)>0:
-				tokens=lines[0].split()
+			with open("channel.inf") as file:
+				lines=file.readlines()
 
-				selServerID=int(tokens[0])
-				selChannelID=int(tokens[1])
-				
-				if len(tokens) == 3:
-					regionID = int(tokens[2])
+				if len(lines)>0:
+					tokens=lines[0].split()
 
-				return regionID, selServerID, selChannelID
+					selServerID=int(tokens[0])
+					selChannelID=int(tokens[1])
+
+					if len(tokens) == 3:
+						regionID = int(tokens[2])
+
+					return regionID, selServerID, selChannelID
 
 		except:
 			print "LoginWindow.__LoadChannelInfo - OpenError"
-			return -1, -1, -1
+		return -1, -1, -1
 
 	def __ExitGame(self):
 		app.Exit()
diff --git a/assets/root/mousemodule.py b/assets/root/mousemodule.py
index 1413f4b8..711febcb 100644
--- a/assets/root/mousemodule.py
+++ b/assets/root/mousemodule.py
@@ -27,7 +27,8 @@ class CursorImage(object):
 		self.LoadImage(imageName)
 
 	def __del__(self):
-		grpImage.Delete(self.handle)
+		if grpImage and self.handle:
+			grpImage.Delete(self.handle)
 
 	def LoadImage(self, imageName):
 		try:
diff --git a/assets/root/musicinfo.py b/assets/root/musicinfo.py
index 2b980fbf..4eb8ff05 100644
--- a/assets/root/musicinfo.py
+++ b/assets/root/musicinfo.py
@@ -9,21 +9,19 @@ def SaveLastPlayFieldMusic():
 	global fieldMusic
 
 	try:
-		lastPlayFile=open("BGM/lastplay.inf", "w")
+		with open("BGM/lastplay.inf", "w") as lastPlayFile:
+			lastPlayFile.write(fieldMusic)
 	except IOError:
 		return
 
-	lastPlayFile.write(fieldMusic)
-
 
 def LoadLastPlayFieldMusic():
 	global fieldMusic
 
 	try:
-		lastPlayFile=open("BGM/lastplay.inf", "r")
+		with open("BGM/lastplay.inf", "r") as lastPlayFile:
+			fieldMusic=lastPlayFile.read()
 	except IOError:
 		return
 
-	fieldMusic=lastPlayFile.read()
-
 
diff --git a/assets/root/system.py b/assets/root/system.py
index 79df485d..9f2a8ec2 100644
--- a/assets/root/system.py
+++ b/assets/root/system.py
@@ -22,7 +22,8 @@ class LogBoxFile:
 		self.restore()
 
 	def restore(self):
-		sys.stderr = self.stderrSave
+		if sys:
+			sys.stderr = self.stderrSave
 
 	def write(self, msg):
 		self.msg = self.msg + msg
diff --git a/assets/root/ui.py b/assets/root/ui.py
index 36645afc..c5c8cc0a 100644
--- a/assets/root/ui.py
+++ b/assets/root/ui.py
@@ -98,7 +98,8 @@ class Window(object):
 		self.Hide()
 
 	def __del__(self):
-		wndMgr.Destroy(self.hWnd)
+		if wndMgr and self.hWnd:
+			wndMgr.Destroy(self.hWnd)
 
 	def RegisterWindow(self, layer):
 		self.hWnd = wndMgr.Register(self, layer)
diff --git a/assets/root/uitaskbar.py b/assets/root/uitaskbar.py
index d413e3df..d0b2f644 100644
--- a/assets/root/uitaskbar.py
+++ b/assets/root/uitaskbar.py
@@ -26,11 +26,13 @@ def GetMouseButtonSettings():
 
 def SaveMouseButtonSettings():
 	global MOUSE_SETTINGS
-	open("mouse.cfg", "w").write("%s\t%s" % tuple(MOUSE_SETTINGS))
+	with open("mouse.cfg", "w") as f:
+		f.write("%s\t%s" % tuple(MOUSE_SETTINGS))
 
 def LoadMouseButtonSettings():
 	global MOUSE_SETTINGS
-	tokens = open("mouse.cfg", "r").read().split()
+	with open("mouse.cfg", "r") as f:
+		tokens = f.read().split()
 
 	if len(tokens) != 2:
 		raise RuntimeError, "MOUSE_SETTINGS_FILE_ERROR"
diff --git a/assets/root/uiuploadmark.py b/assets/root/uiuploadmark.py
index a0defa0b..cfcaa962 100644
--- a/assets/root/uiuploadmark.py
+++ b/assets/root/uiuploadmark.py
@@ -6,11 +6,14 @@ import uiScriptLocale
 class MarkItem(ui.ListBoxEx.Item):
 	def __init__(self, fileName):
 		ui.ListBoxEx.Item.__init__(self)
-		self.imgWidth=0
-		self.imgHeight=0
-		self.canLoad=0
-		self.textLine=self.__CreateTextLine(fileName)
-		self.imgBox=self.__CreateImageBox("upload/"+fileName)
+		self.fileName = fileName
+		self.fullPath = "upload/" + fileName
+		self.imgWidth = 0
+		self.imgHeight = 0
+		self.canLoad = 0
+		self.imgBox = None
+		self.imageLoaded = False
+		self.textLine = self.__CreateTextLine(fileName)
 
 	def __del__(self):
 		ui.ListBoxEx.Item.__del__(self)
@@ -22,35 +25,47 @@ class MarkItem(ui.ListBoxEx.Item):
 		ui.ListBoxEx.Item.SetSize(self, 20 + 6*len(self.textLine.GetText()) + 4, height)
 
 	def __CreateTextLine(self, fileName):
-		textLine=ui.TextLine()
+		textLine = ui.TextLine()
 		textLine.SetParent(self)
 		textLine.SetPosition(20, 0)
 		textLine.SetText(fileName)
 		textLine.Show()
 		return textLine
 
-	def __CreateImageBox(self, fileName):
-		(self.canLoad, self.imgWidth, self.imgHeight)=app.GetImageInfo(fileName)
+	def LoadImageInfo(self):
+		"""Load image info lazily when needed (e.g., when selected or validated)"""
+		if self.imageLoaded:
+			return
 
-		if 1==self.canLoad:
-			if 16==self.imgWidth and 12==self.imgHeight:
-				imgBox=ui.ImageBox()
-				imgBox.AddFlag("not_pick")
-				imgBox.SetParent(self)
-				imgBox.SetPosition(0, 2)
-				imgBox.LoadImageFromFile(fileName)
-				imgBox.Show()
-				return imgBox
-			else:
-				return 0
-		else:
-			return 0
+		self.imageLoaded = True
+		(self.canLoad, self.imgWidth, self.imgHeight) = app.GetImageInfo(self.fullPath)
+
+		if self.canLoad == 1 and self.imgWidth == 16 and self.imgHeight == 12:
+			imgBox = ui.ImageBox()
+			imgBox.AddFlag("not_pick")
+			imgBox.SetParent(self)
+			imgBox.SetPosition(0, 2)
+			imgBox.LoadImageFromFile(self.fullPath)
+			imgBox.Show()
+			self.imgBox = imgBox
+
+	def OnRender(self):
+		# Load image when item becomes visible (rendered)
+		if not self.imageLoaded:
+			self.LoadImageInfo()
+		# Call parent to draw selection bar
+		ui.ListBoxEx.Item.OnRender(self)
 
 class SymbolItem(ui.ListBoxEx.Item):
 	def __init__(self, fileName):
 		ui.ListBoxEx.Item.__init__(self)
-		self.textLine=self.__CreateTextLine(fileName)
-		(self.canLoad, self.imgWidth, self.imgHeight)=app.GetImageInfo("upload/"+fileName)
+		self.fileName = fileName
+		self.fullPath = "upload/" + fileName
+		self.imgWidth = 0
+		self.imgHeight = 0
+		self.canLoad = 0
+		self.imageLoaded = False
+		self.textLine = self.__CreateTextLine(fileName)
 
 	def __del__(self):
 		ui.ListBoxEx.Item.__del__(self)
@@ -62,13 +77,28 @@ class SymbolItem(ui.ListBoxEx.Item):
 		ui.ListBoxEx.Item.SetSize(self, 6*len(self.textLine.GetText()) + 4, height)
 
 	def __CreateTextLine(self, fileName):
-		textLine=ui.TextLine()
+		textLine = ui.TextLine()
 		textLine.SetParent(self)
 		textLine.SetPosition(1, 2)
 		textLine.SetText(fileName)
 		textLine.Show()
 		return textLine
 
+	def LoadImageInfo(self):
+		"""Load image info lazily when needed"""
+		if self.imageLoaded:
+			return
+
+		self.imageLoaded = True
+		(self.canLoad, self.imgWidth, self.imgHeight) = app.GetImageInfo(self.fullPath)
+
+	def OnRender(self):
+		# Load image when item becomes visible (rendered)
+		if not self.imageLoaded:
+			self.LoadImageInfo()
+		# Call parent to draw selection bar
+		ui.ListBoxEx.Item.OnRender(self)
+
 class PopupDialog(ui.ScriptWindow):
 	def __init__(self, parent):
 		print "NEW POPUP WINDOW   ----------------------------------------------------------------------------"	
@@ -193,13 +223,16 @@ class MarkSelectDialog(ui.ScriptWindow):
 		self.popupDialog.Open(msg)
 
 	def __OnOK(self):
-		selItem=self.markListBox.GetSelectedItem()
+		selItem = self.markListBox.GetSelectedItem()
 		if selItem:
-			if selItem.canLoad!=1:
+			# Ensure image info is loaded before validation
+			selItem.LoadImageInfo()
+
+			if selItem.canLoad != 1:
 				self.__PopupMessage(localeInfo.GUILDMARK_UPLOADER_ERROR_FILE_FORMAT)
-			elif selItem.imgWidth!=16:
+			elif selItem.imgWidth != 16:
 				self.__PopupMessage(localeInfo.GUILDMARK_UPLOADER_ERROR_16_WIDTH)
-			elif selItem.imgHeight!=12:
+			elif selItem.imgHeight != 12:
 				self.__PopupMessage(localeInfo.GUILDMARK_UPLOADER_ERROR_12_HEIGHT)
 			else:
 				self.selectEvent(selItem.GetText())
@@ -215,20 +248,22 @@ class MarkSelectDialog(ui.ScriptWindow):
 
 	def __RefreshFileList(self):
 		self.__ClearFileList()
-		self.__AppendFileList("bmp")
-		self.__AppendFileList("tga")
-		self.__AppendFileList("jpg")
-		self.__AppendFileList("jpeg")
-		self.__AppendFileList("png")
+		# Collect all files first, then batch add to avoid multiple UI updates
+		allFiles = []
+		for ext in ("bmp", "tga", "jpg", "jpeg", "png"):
+			fileNameList = app.GetFileList("upload/*." + ext)
+			allFiles.extend(fileNameList)
+
+		# Sort alphabetically for consistent display
+		allFiles.sort()
+
+		# Add all files at once
+		for fileName in allFiles:
+			self.__AppendFile(fileName)
 
 	def __ClearFileList(self):
 		self.markListBox.RemoveAllItems()
 
-	def __AppendFileList(self, filter):
-		fileNameList=app.GetFileList("upload/*."+filter)
-		for fileName in fileNameList:
-			self.__AppendFile(fileName)
-
 	def __AppendFile(self, fileName):
 		self.markListBox.AppendItem(MarkItem(fileName))
 
@@ -318,13 +353,16 @@ class SymbolSelectDialog(ui.ScriptWindow):
 		self.popupDialog.Open(msg)
 
 	def __OnOK(self):
-		selItem=self.symbolListBox.GetSelectedItem()
+		selItem = self.symbolListBox.GetSelectedItem()
 		if selItem:
-			if selItem.canLoad!=1:
+			# Ensure image info is loaded before validation
+			selItem.LoadImageInfo()
+
+			if selItem.canLoad != 1:
 				self.__PopupMessage(localeInfo.GUILDMARK_UPLOADER_ERROR_FILE_FORMAT)
-			elif selItem.imgWidth!=64:
+			elif selItem.imgWidth != 64:
 				self.__PopupMessage(localeInfo.GUILDMARK_UPLOADER_ERROR_64_WIDTH)
-			elif selItem.imgHeight!=128:
+			elif selItem.imgHeight != 128:
 				self.__PopupMessage(localeInfo.GUILDMARK_UPLOADER_ERROR_128_HEIGHT)
 			else:
 				self.selectEvent(selItem.GetText())
diff --git a/assets/root/utils.py b/assets/root/utils.py
index 7906f29c..90c0b2e3 100644
--- a/assets/root/utils.py
+++ b/assets/root/utils.py
@@ -46,10 +46,10 @@ class Sandbox(object):
 			sys.modules[prevented_module_name] = None
 		
 		try:
-			f = open(filename, 'rb')
-			data = f.read()
-			code = compile(data, filename, 'exec')
-			exec code in dic
+			with open(filename, 'rb') as f:
+				data = f.read()
+				code = compile(data, filename, 'exec')
+				exec code in dic
 		except Exception, e:
 			sys.stderr.write(e)
 		finally: