All designers in the namespace System.Workflow.Activities are internal sealed. For example, I cannot derive from IfElseDesigner.
Why?
How should I customize the look and feel of these designers, if I cannot derive from them?
For a blank ActivityDesigner or CompositeActivityDesigner, I would overwrite OnPaint, but this is not possible for all other designers, isn't it?
<<How should I customize the look and feel of these designers, if I cannot derive from them? >>
Mario,
code of IfElsedesigner seems simple enough to create your own designer class and to derive it from ParallelActivityDesigner; the most complex method of IfElseDesigner is OnPaint() 
.
Serge
Serge,
it would be much easier, if one could derive from IfElseDesigner (and others).
It is not only the OnPaint method. For example, there are eight classes starting with IfElse in the System.Workflow.Activities namespace, which control important behaviour of IfElseActivity and they are all sealed or private.
If I would like to ensure my activity to have the same behaviour and almost the same look-and-feel as IfElseActivity[Designer], then my only chance at the moment is to reinvent the wheel, right?
And if something changes in the IfElse APIs, my derivatives of CompositeActivity or ParallelActivityDesigner will not inherit these changes. Further more, I will not even have a chance to take over changes from IfElse classes to my own derivatives, because I would not get informed about something has changed.
Kind Regards,
Mario
Mario,
Thank you for your feedback. I passed your ask for customization capabilities to the Designer Product team.
Laurence
