Thank you for the question.
I am not sure what exactly your scenario is, but if you concern MDI, I was not able to reproduce the issue. Each time I select a document containing a form, this form fires the GotFocus event. Only the first time, when the documents get loaded you do not get the GotFocus event fired, because of the cycle that transfers the MDI children to normal docked windows.
If you want to get an event fired even in the case where the document windows are loaded for the first time, you can handle the ActiveWindowChanged event. I am attaching a sample project which demonstrates the approach.
I hope your find this information helpful.
the Telerik team