It seems that it is not possible to use Extension methods with xojo.Core.Dictionary?
It works here. Make sure you create your extends method on a module.
[code]Module Module1
Sub Test(Extends d As xojo.Core.Dictionary)
MsgBox CurrentMethodName
End Sub
End Module
// In App.Open() event
Dim d As New xojo.Core.Dictionary()
d.Test()[/code]
Thanks für your answers.
It works, but I have no code completion.