I'm glad I found this buried here in the forums, I've been trying to construct a level editor for a while and was making a clumsy attempt of it using XNA only for the GUI.
The graphics device controls on my windows form keep vanishing after I have been working on another form element unrelated to the graphics device control.
I add a graphics device control into the body of a tab form, and set it up to display a simple texture2D type - if I test it at this point it works fine.
I then add a combiBox to the form, do some work on it like manually adding in list text (I was trying to get the list from a set of dictionary keys - but that is another topic)
All looks well, I click off to edit the form code (not the designer code) and when I return my sprite control no longer exists.
When I review the form designer code, my sprite control is no longer one of the items initialised, however the object declaration is still there.
Just to make it more confusing this doesn't happen every time, I think it may be to do with which parts of an element I am updating properties to. Sometimes the control is visible on the form but can no longer be selected.
The only work around I can think of is to add my graphics device controls at the end, which doesn't help me with testing each one as I do it.
Am I missing something really obvious here? Truth be told it has been ages sinced I have worked with forms.