How to customize the length of the text field in the dialog box?

When I want to save a file from a website and choose "Save as" in the browser that I am using, a dialog box appears that allows me to choose the place and the name with which to save the file.

However, the text field that contains the file name is quite short, since it shows approximately 50 characters, and it remains that way even if you increase the width of the "Save as" dialog box (see image included). This is something of a nuisance when dealing with long filenames.

Is there any way to customize the length of this text field?

I am running Ubuntu 18.10.