It does change the task bar icon. Tested with this code:
B4X:
'BitmapCreator and XUI
Dim bc As BitmapCreator
bc.Initialize(32, 32)
For i = 1 To 100
bc.DrawRect(bc.TargetRect, Rnd(0xff000000, -1), True, 0)
MainForm.Icon = bc.Bitmap
Sleep(1000)
Next
It does change the task bar icon. Tested with this code:
B4X:
'BitmapCreator and XUI
Dim bc As BitmapCreator
bc.Initialize(32, 32)
For i = 1 To 100
bc.DrawRect(bc.TargetRect, Rnd(0xff000000, -1), True, 0)
MainForm.Icon = bc.Bitmap
Sleep(1000)
Next