Hi,
It like that this issue only happens on firefox browser, when testing on chrome/IE, the scrollbar works fine. by the way, it is resizable even using on firefox. I will report to the development team and improve it in the future version.
And do not need to change the code in "CuteSoft_Client\CuteEditor\Scripts\Constant.js", the settings only use for the default mode. The UseStandardDialog mode using "editor.ShowDialog()" to opens the dialog, this code has been Encrypted in a js file, so can not change from your end directly for now.
Regards,
Ken