Since some version WinSCP supports editing filenames on single click: when I click on a file a text field appears and I can edit its name. This is similar to Windows Explorer, if you selected the option. While that feature may seem cool, I found that in my specific case when I click filenames and WinSCP shows the text field 9 out of 10 times that was not my intention to edit it. I was either to select the file or to just focus WinSCP. All I do then is just hit Esc or click somewhere else to cancen editing. That's not a big deal yet eventually it gets irritating. Also, when you know it's gonna edit it, you start avoiding clicking anywhere and have to carefully select a place to click (for example to select a file), and that's just strange cause the program is good otherwise.
My suggestion is to offer this feature as an option, like it is in Windows Explorer. Editing filenames really is a seldom operation.