[BUG] Problems with 'Custom Headers' and 'Custom Cookies' boxes

[APT-ZERO]

Write a line in 'Custom Headers' or 'Custom Cookies' then select the whole Line Delete now 'CTRL + Z' will not bring that line back

also sometimes when i want to edit a line, whole line will removed!

there is another Multi line boxes too ( for example: 'Custom Cipher Suites'), but there is no problem with them