System.InvalidOperationException thrown by System.Drawing

[magicRoot]

Hi

My Windows Forms program exits with the following error:

 

An unhandled exception of type 'System.InvalidOperationException' occurred in System.Drawing.dll

 

Additional information: Object is currently in use elsewhere.

 

My program consists of a tabControl component with two tabs. The first tab has a picture box where I constantly place new images. The second tab has other stuff. Everything works fine when I remain in the first tab and continuously place images in the picture box, but if I switch to the second tab, then back to the first, I get the error stated. There is another thread apart from the UI thread that does the actual placement of images in the picturebox. What is causing the error?

[PlausiblyDamp]

Is the other thread actually updating the UI? If so this is likely the problem as you should only update the UI from the UI thread.

[magicRoot]

yes, the worker thread does place the images in the picture box, but not directly; it uses a delegate method to call a setter function in the UI thread to change the image. I had the same error before due to the worker thread changing UI components directly. I added delegates to fix that. This error on the other hand is caused while in the UI thread. any ideas?

[magicRoot]

would calling a static function in the UI thread from the worker thread be considered thread-unsafe?

[magicRoot]

it seems that a method call in the worker thread was causing the exception. I think that method was making a system call internally, which was the source of the exception. Thanks for the hint.