Why not use Powermenu or anything alike and add tis feature yourself.
thanks mate, i read in another thread in here, that this is not working correctly. thats why. :-)
https://winscp.net/forum/viewtopic.php?t=1773
I downloaded a seperate minimize to systray utility for this purpose (PowerMenu), but unfortunately it minimizes only the small "extra" window to the systray (which isn't shown at all when just minimizing), still leaving the main program icon to crowd my taskbar.
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