FolderBrowserDialog - Thread Problem?

I'm seriously about to pull my hair out. I've been trying for hours to get this thing to work.

What I'm doing
Doing a folder browse operation from a Context Menu on the same form.

Private Sub Playlist_FolderAdd(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MenuItem8.Click
Dim b As New FolderBrowserDialog
b.Description = "Select a folder containing media."
b.ShowNewFolderButton = False
b.RootFolder = Environment.SpecialFolder.Desktop

If b.ShowDialog = DialogResult.OK Then
Debug.WriteLine(b.SelectedPath)
End If
End Sub

Exception Thrown:

System.Runtime.InteropServices.SEHException: External component has thrown an exception.
at System.Windows.Forms.Shell32.SHBrowseForFolder(BROWSEINFO lpbi)
at System.Windows.Forms.FolderBrowserDialog.RunDialog(IntPtr hWndOwner)
at System.Windows.Forms.CommonDialog.ShowDialog()
at Shock.frmMain.Playlist_FolderAdd(Object sender, EventArgs e) in E:\Shock\Shock\Dialogs\frmMain.vb:line 1886
at System.Windows.Forms.MenuItem.OnClick(EventArgs e)
at System.Windows.Forms.MenuItemData.Execute()
at System.Windows.Forms.Command.Invoke()
at System.Windows.Forms.Command.DispatchID(Int32 id)
at System.Windows.Forms.Control.WmCommand(Message& m)
at System.Windows.Forms.Control.WndProc(Message& m)
at System.Windows.Forms.ScrollableControl.WndProc(Message& m)
at System.Windows.Forms.ContainerControl.WndProc(Message& m)
at System.Windows.Forms.Form.WndProc(Message& m)
at System.Windows.Forms.ControlNativeWindow.OnMessage(Message& m)
at System.Windows.Forms.ControlNativeWindow.WndProc(Message& m)
at System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)
at System.Windows.Forms.UnsafeNativeMethods.DispatchMessageW(MSG& msg)
at System.Windows.Forms.ComponentManager.System.Windows.Forms.UnsafeNativ eMethods+IMsoComponentManager.FPushMessageLoop(Int32 dwComponentID, Int32 reason, Int32 pvLoopData)
at System.Windows.Forms.ThreadContext.RunMessageLoopInner(Int32 reason, ApplicationContext context)
at System.Windows.Forms.ThreadContext.RunMessageLoop(Int32 reason, ApplicationContext context)
at System.Windows.Forms.Application.Run(Form mainForm)
at Shock.SubMain.Main() in E:\Shock\Shock\SubMain.vb:line 27


What is very weird is, I put this same exact code in the form load for instance, it'll throw the exception. But if I try the code in another project, works perfectly fine. Could this be a threading issue, some how? Even though everything is called form the same form.

I fixed this problem by making it a Shared Function inside of a Class. I guess that's the way you do it, can anyone explain why?

I think we need some more information. Specifically, which line is generating the error? b.ShowDialog?

The error is likely thrown on the ShowDialog line. Since the error comes from an API that the Folderbrowser component throws, it looks like a bug, unless one of your arguments are incorrect.
Since everything looks okay, I would ask if it worked if you specified the parent control for the ShowDialog or the FolderBrowser.

The error is likely thrown on the ShowDialog line. Since the error comes from an API that the Folderbrowser component throws, it looks like a bug, unless one of your arguments are incorrect.
Since everything looks okay, I would ask if it worked if you specified the parent control for the ShowDialog or the FolderBrowser.

I first had it where I dropped the control from the ToolBox onto the form. Then using it on the same form. It still threw an error. I also tried to reproduce this on another project, it worked fine. Also, it did not highlight any line or nothing when it throws the error.

The try/catch that is producing the error text is

Try
Application.EnableVisualStyles()
Application.DoEvents()
Application.Run(New frmMain)

Catch ex As Exception
Debug.WriteLine(ex.ToString)
End Try

I also tried doing the following line:

If b.ShowDialog(Me) = DialogResult.OK Then

It produces the same behavior.

It loads the Folder dialog up, it'll throw the error if I change the directory or move my mouse off of the dialog itself.

I did however find a fix for this. I created a Shared function inside of a class and it seems to work like a champ. I'm sorry I cannot give you any more details than what I have provided. It's very werid.

I've also had some problems where if I close a dialog and there is a list on the form, it will throw an error everytime. "Cannot access disposed object "ListBox". I think maybe the project is messed up or something :whoops:

If you guys are really wanting to solve/look at the issue at hand, I can provide the full source code. Email me: intolerance at gmail dot com

Can you post it here?