wrong application focus after close "File Compare" in 5.5

Steps:
1. focus any third application;
2. focus WinSCP;
3. compare any files in WinSCP (built-in compare tool or any other);
4. close "File Compare" window.

Exp: WinSCP focused.

Act: third application focused.

Thanks for your report.

This is side-effect on this bug:
https://winscp.net/tracker/1101