Get rid of windowname , how?

[c.poupin]

Hi,
Set the TitleAutoPrefix property to False

import clr

clr.AddReference('RevitAPIUI')
from Autodesk.Revit.UI import TaskDialog

concat = '\n'.join(["A","B","C"])
dialog = TaskDialog("MyAddin - Test")
dialog.MainInstruction = concat
dialog.TitleAutoPrefix = False
dialog.Show()