RichTextBox access error ?

  • Thread starter Thread starter vertigo
  • Start date Start date
V

vertigo

Hello
I have some Threads, and they write something to
RichTextBox.Text property. But sometimes i receive error:

************** Exception Text **************
System.NullReferenceException: Object reference not set to an instance
of an object.
at System.Windows.Forms.RichTextBox.EditStreamProc(IntPtr dwCookie,
IntPtr buf, Int32 cb, Int32& transferred)
at System.Windows.Forms.UnsafeNativeMethods.CallWindowProc(IntPtr
wndProc, IntPtr hWnd, Int32 msg, IntPtr wParam, IntPtr lParam)
at System.Windows.Forms.NativeWindow.DefWndProc(Message& m)
at System.Windows.Forms.Control.DefWndProc(Message& m)
at System.Windows.Forms.Control.WndProc(Message& m)
at System.Windows.Forms.TextBoxBase.WndProc(Message& m)
at System.Windows.Forms.RichTextBox.WndProc(Message& m)
at System.Windows.Forms.ControlNativeWindow.OnMessage(Message& m)
at System.Windows.Forms.ControlNativeWindow.WndProc(Message& m)
at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32
msg, IntPtr wparam, IntPtr lparam)

Why ? Is it problem with synchronization: that many threads try to
change Text property at the same time, or what ?
How can i solve this problem ?

Thanx
Michal
 
vertigo,

if you access any UI control from threads you might have similar problems.
Most of UI controls are single-threaded by definition and you can safely
access them only from UI thread.

HTH
Alex
 
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