"Herfried K. Wagner [MVP]" <hirf-spam-me-here@gmx.at> wrote in message
news:ucj6rBTkGHA.4660@TK2MSFTNGP05.phx.gbl...
> "ljh" <Reply@groups.please> schrieb:
>>I am trying to run some pretty simple code that monitors a folder for
>>changes (copied the example at
>>http://www.codeproject.com/dotnet/folderwatcher.asp).
>>
>> But, when I try and update a textbox control I keep getting the
>> "Cross-thread operation not valid: Control 'txt_folderactivity' accessed
>> from a thread other than the thread it was created on." error.
>
> Set the filesystemwatcher's 'SynchronizingObject' property to the textbox.
>
> --
> M S   Herfried K. Wagner
> M V P  <URL:http://dotnet.mvps.org/>
> V B   <URL:http://classicvb.org/petition/>

> I am trying to run some pretty simple code that monitors a folder for
> changes (copied the example at
> http://www.codeproject.com/dotnet/folderwatcher.asp).
>
> But, when I try and update a textbox control I keep getting the
> "Cross-thread operation not valid: Control 'txt_folderactivity' accessed
> from a thread other than the thread it was created on." error.
>
> I found the Microsoft explanation at
> http://msdn2.microsoft.com/en-us/library/ms171728(VS.80,d=ide).aspx, but I
> just don't get the explanation.
>
> Can somebody help me understand why I can't simply set the text property
> from a thread and what this Microsoft explanation is trying to tell me?
>
> Thanks!

"Brian Gideon" <briangid***@yahoo.com> wrote in message
news:1150497582.558072.236520@i40g2000cwc.googlegroups.com...
> Windows forms and controls can only be accessed from the thread they
> were created on.  That is the main UI thread.  The FileSystemWatcher
> events come from some other thread.  The cross-thread operation error
> you see is coming from a Managed Debugging Assistant (MDA) which is
> nice enough to warn you of the potential problem in debug builds.  MDAs
> are not compiled into release builds.  They are a new feature in 2.0.
>
> Setting the SynchronizingObject property to a Form or Control in your
> application tells the FileSystemWatcher to automatically marshal the
> execution of events onto the thread that created that form or control.
>
> ljh wrote:
>> I am trying to run some pretty simple code that monitors a folder for
>> changes (copied the example at
>> http://www.codeproject.com/dotnet/folderwatcher.asp).
>>
>> But, when I try and update a textbox control I keep getting the
>> "Cross-thread operation not valid: Control 'txt_folderactivity' accessed
>> from a thread other than the thread it was created on." error.
>>
>> I found the Microsoft explanation at
>> http://msdn2.microsoft.com/en-us/library/ms171728(VS.80,d=ide).aspx, but
>> I
>> just don't get the explanation.
>>
>> Can somebody help me understand why I can't simply set the text property
>> from a thread and what this Microsoft explanation is trying to tell me?
>>
>> Thanks!
>