>>>>>Hello!
>>>>>
>>>>>via
>>>>>_screen.icon = "iconX.ico"
>>>>>
>>>>>I can easy change the Icon dynamically.
>>>>>Bud the Taskbar always shows the old Icon.
>>>>>
>>>>>Is there a API Call to force the Taskbar to do so?
>>>>
>>>>It works over here, both IDE and runtime
>>>
>>>Which Windows Version?
>>>I've Windows 10 1709
>>
>>Windows 10 also
>
>??
>For me it doesn't work

Maybe due the dimensions of the icon file. Try with a couple of others