Creating new file issue

[dakiriki]

Hi.
In ST 3143, when I want to create the new file, I was able to do this:

• right click on folder in sidebar > new file
• type name of file like myNewFileName.js
  and save it with that name

Now file name in save dialog gets cut, on some random number of characters, sometimes is just an extension, sometimes more.
Is this a bug?

Arch Linux 64, ST 3143

Thank you.