[Mono-bugs] [Bug 417174] New: CheckForIllegalCrossThreadCalls prevents use of Control. Invoke

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https://bugzilla.novell.com/show_bug.cgi?id=417174


           Summary: CheckForIllegalCrossThreadCalls prevents use of
                    Control.Invoke
           Product: Mono: Class Libraries
           Version: 1.9
          Platform: 32bit
        OS/Version: Linux
            Status: NEW
          Severity: Normal
          Priority: P5 - None
         Component: Windows.Forms
        AssignedTo: mono-bugs at lists.ximian.com
        ReportedBy: andre at masella.no-ip.org
         QAContact: mono-bugs at lists.ximian.com
          Found By: ---


Created an attachment (id=233340)
 --> (https://bugzilla.novell.com/attachment.cgi?id=233340)
C# Test Case

I have experienced this problem on Mono 1.9 and 1.9.1. On a Windows.Forms based
application, if System.Windows.Forms.Control.CheckForIllegalCrossThreadCalls =
true, then trying to Invoke a delegate of an instantiated control will give the
exception System.InvalidOperationException: Cross-thread access of handle
detected. Handle access only valid on thread that created the control.

If the Invoke method of a control cannot be called from another thread, it
becomes difficult to communicate between worker threads and the GUI.

I have attached a test case. It gives the following output:
Starting Thread
Thread Started
Running Application
Invoking cross-thread

Unhandled Exception: System.InvalidOperationException: Cross-thread access of
handle detected. Handle access only valid on thread that created the control
  at System.Windows.Forms.Control.get_Handle () [0x00000]
  at (wrapper remoting-invoke-with-check)
System.Windows.Forms.Control:get_Handle ()
  at System.Windows.Forms.Control.BeginInvokeInternal (System.Delegate method,
System.Object[] args, System.Windows.Forms.Control control) [0x00000]
  at System.Windows.Forms.Control.Invoke (System.Delegate method,
System.Object[] args) [0x00000]
  at (wrapper remoting-invoke-with-check) System.Windows.Forms.Control:Invoke
(System.Delegate,object[])
  at System.Windows.Forms.Control.Invoke (System.Delegate method) [0x00000]
  at (wrapper remoting-invoke-with-check) System.Windows.Forms.Control:Invoke
(System.Delegate)
  at Test.ThreadTask () [0x00000]

It seems that the Invoke method is causing the cross-thread access by trying to
get the handle of the control.

If I set CheckForIllegalCrossThreadCalls = false, it works on Mono. It will
works either way on Microsoft .NET 2.0SP1.


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