[mono-vb] System.NullReferenceException: Object reference not set to an instance of an object at System.Windows.Forms.TreeView.MouseMoveHandler when dragging a node in a treeview

[Stifu]

I just tried your app...

With .NET, it won't start due to the fact you didn't include the
Mono.Data.Sqlite.dll file with your project. Shouldn't you do so if you want
your app to be "Platform-Independent"?

With Mono 2.4 on Windows, I also get an error on start up.
Have a look: http://stifu.free.fr/pics/temp/repetit_error.png


Easy_Rider9999 wrote:
> 
> I am always getting this error, when dragging a node in my treeview. I
> reported this error to Novell, but they say, that they can't reproduce it.
> I get this Error with Mono 2.4 (both windows and Ubuntu 8.04). Is anybody
> there that can reproduce this error? You can get my application at
> https://sourceforge.net/project/showfiles.php?group_id=257087&package_id=315752&release_id=675230
> 
> This is the Error message:
> 
> System.NullReferenceException: Object reference not set to an instance of
> an obj
> ect
>   at System.Windows.Forms.TreeView.MouseMoveHandler (System.Object sender,
> Syste
> m.Windows.Forms.MouseEventArgs e) [0x0015a] in
> C:\cygwin\tmp\monobuild\build\BUI
> LD\mono-2.4\mcs\class\Managed.Windows.Forms\System.Windows.Forms\TreeView.cs:223
> 0
>   at (wrapper delegate-invoke)
> System.Windows.Forms.MouseEventHandler:invoke_voi
> d__this___object_MouseEventArgs
> (object,System.Windows.Forms.MouseEventArgs)
>   at System.Windows.Forms.Control.OnMouseMove
> (System.Windows.Forms.MouseEventAr
> gs e) [0x0001c] in
> C:\cygwin\tmp\monobuild\build\BUILD\mono-2.4\mcs\class\Manage
> d.Windows.Forms\System.Windows.Forms\Control.cs:6382
>   at System.Windows.Forms.Control.WmMouseMove
> (System.Windows.Forms.Message& m)
> [0x00064] in
> C:\cygwin\tmp\monobuild\build\BUILD\mono-2.4\mcs\class\Managed.Wind
> ows.Forms\System.Windows.Forms\Control.cs:5783
>   at System.Windows.Forms.Control.WndProc (System.Windows.Forms.Message&
> m) [0x0
> 01d4] in
> C:\cygwin\tmp\monobuild\build\BUILD\mono-2.4\mcs\class\Managed.Windows.
> Forms\System.Windows.Forms\Control.cs:5387
>   at System.Windows.Forms.TreeView.WndProc (System.Windows.Forms.Message&
> m) [0x
> 0006b] in
> C:\cygwin\tmp\monobuild\build\BUILD\mono-2.4\mcs\class\Managed.Windows
> .Forms\System.Windows.Forms\TreeView.cs:1198
>   at System.Windows.Forms.Control+ControlWindowTarget.OnMessage
> (System.Windows.
> Forms.Message& m) [0x00000] in
> C:\cygwin\tmp\monobuild\build\BUILD\mono-2.4\mcs\
> class\Managed.Windows.Forms\System.Windows.Forms\Control.cs:234
>   at System.Windows.Forms.Control+ControlNativeWindow.WndProc
> (System.Windows.Fo
> rms.Message& m) [0x00000] in
> C:\cygwin\tmp\monobuild\build\BUILD\mono-2.4\mcs\cl
> ass\Managed.Windows.Forms\System.Windows.Forms\Control.cs:215
>   at System.Windows.Forms.NativeWindow.WndProc (IntPtr hWnd, Msg msg,
> IntPtr wPa
> ram, IntPtr lParam) [0x00085] in
> C:\cygwin\tmp\monobuild\build\BUILD\mono-2.4\mc
> s\class\Managed.Windows.Forms\System.Windows.Forms\NativeWindow.cs:242
> frmMain.tvMed_BeforeSelect Start
> frmMain.Form_Activate Start
> 
> Regards 
> 
> Hans
> 

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