Private Messages: Scroll appears on creating long subject without spaces

Steps to reproduce:

1. Create a message. In the "Subject" enter the text and save.

aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa

2. Open "Drafts" folder.

Actual result: Page stretched, horizontal scroll appears.

Expected result:

• Message about the impossibility to save more than 120 characters
• no horizontal scroll appears