Cannot%20focus%20a%20disabled%20or%20invisible%20window%0D%0A%0D%0AStack%20trace%3A%0D%0A%28001DBBED%29%20Vcl%3A%3AForms%3A%3ATCustomForm%3A%3ASetFocus

Dragged a small text file from the desktop to the remote host pane.

WinSCP 5.7.7

Error message:
Cannot%20focus%20a%20disabled%20or%20invisible%20window%0D%0A%0D%0AStack%20trace%3A%0D%0A%28001DBBED%29%20Vcl%3A%3AForms%3A%3ATCustomForm%3A%3ASetFocus

Status: not_matched

The problem happens rarely. I cannot reproduce it.