Can not save changes in Settings -> Network after trying to add command-line option to the SSH-client

What steps will reproduce the problem?

1. Invoke the Settings dialog for TortoiseGit
2. Goto Network page
3. Add the "-A" command-line option to the SSH-client (TortoiseGit\bin\TortoiseGitPlink.exe)
4. Try to click on "Apply" or "Ok" buttons

What is the expected output? What do you see instead?

The dialog must either accept the changes or show a relevant error message. Instead the dialog does not react on clicking OK or APPLY - but reacts on clicking CLOSE or HELP.

What version of TortoiseGit and Git are you using? On what operating system?

This is TortoiseGit 2.5.0.0 (D:\PROGRAM\TortoiseGit\bin) git version 2.10.0.windows.1 (D:\PROGRAM\Git\git\bin; D:\PROGRAM\Git\git\mingw32; D:\PROGRAM\Git\git\mingw32\etc\gitconfig; C:\ProgramData\Git\config) used on Windows 7 SP1 x64

Please provide any additional information below.