I finally figured out what 'diegot' is talking about. (took a bit though, because his description is a bit vague).
Basically, if you're using Process Template Editor to register the WebBrowserControl, a curious behaviour of the editor (within Process Template Editor) is that it trims anything where a second "equals" sign is encountered. I.e. you may have put
but when you view it in the XML, it has cleared the value
<Control Type="WebBrowserControl" Label="Basic custom label:" LabelPosition="Top" Dock="Fill" URL="http://bbwk35/TFSCargaHoras/Default.aspx?WorkItem" Params="System.ID" />
So this is actually a bug in the Process Template Editor, not in the WitCustomControl code.
I suggest the workaround (which works for us) is to put the value in the keyname ... i.e. without the equals sign. you could use your own delimiter, so long as the code on the Default.aspx page knows how to iterate through the keys of the Request.QueryString
object. i.e. the data is being passed in the name rather than the value but that's okay because it bypasses the problem.
This approach worked for our implementation, hope it helps someone else who is encountering the same issue.