1) CTRL-Click on the WinSCP window in the Windows taskbar to select it.
2) CTRL-Click on at least one more application in the taskbar to select it also.
3) Right click on one of the selected windows.
4) Click one of the auto-arrange options such as "Show Windows Side By Side".
WinSCP seems to ignore the resizing but the other selected app (such as Windows Explorer) will behave as expected. I would love to see this feature work correctly for nicely arranging a local browser (Windows Explorer) and a remote browser (WinSCP) nicely for drag and drop operations.