If the remote site has a large file which you then double click on in the WinSCP panel, eventually the editor runs out of memory. An error popup is generated to this effect. However, when the popup is dismissed, it reappears again. Clicking the (x) in the upper right corner of the edit window does nothing. Using Task Manager to try to terminate the edit process is also unsuccessful. The main WinSCP process has to be terminated and WinSCP restarted.
It appears that WinSCP fails to understand that this is a terminal error condition for the editor, and it should stop trying to load the data. Probably, the edit window should be automatically dismissed when the error popup is dismissed, or edit process should at least be halted.
WinSCP version: 5.5.3 (Build 4214)
OS: Win10 x64