Restoring windows in [Design] mode when solution is opened

[RobertvanderHulst]

For our custom language (X#) we also support the Windows Forms Editor.

When a user closes a solution that has a window in design mode (which you can recognize with Form1 [Design] for example, then when re-opening the solution the windows in design mode are not reopened properly.

You do see the document tabs with "Form1 [Design]" and "Form2 [Design]" but the contents of these tabs is not properly shown.
You see an error message such as this one:

We have now added an event handler to our solution that runs from the Toolkits OnAfterBackgroundSolutionLoadComplete event and inside that event handler we enumerate the document windows with
var documents = await VS.Windows.GetAllDocumentWindowsAsync();
and then detect the windows that are in design mode by inspecting their captions.
For the windows in design mode we get the filename by querying for __VSFPROPID.VSFPROPID_pszMkDocument and we close these with
await doc.CloseFrameAsync(FrameCloseOption.SaveIfDirty);

Afterward we open all the windows that were closed by us again specifying that we want to open them in Design mode.
We have a helper method that takes care of that.

VsShellUtilities.OpenDocument(ServiceProvider.GlobalProvider, file, VSConstants.LOGVIEWID_Designer, out _, out _, out _);

This works and looks great, if and when the current selected document is a 'normal' source code document.
When the selected document is in design mode then the enumeration of the documents does not return all the windows that are open in design mode.

I have 2 questions:

• Can anyone explain why GetAllDocumentWindowsAsync() does not include some of the windows in [Design] mode when the current selected document itself is in [Design] mode ?
• Is this the right way to do this, or is there a better solution?