Application freeze

Hi Dennis,

Usually, in such situations, the cause of this issue is the same - an event handler subscribes to the SystemEvents.OnUserPreferenceChanged event in a non UI thread before an event handler subscribes to this event in an UI thread. As a result, an incorrect synchronization context is captured. This behavior can take place, for instance, if any DevExpress control is created in a non UI thread.
See the App Hang OnUserPreferenceChanged and UI not responding after a few minutes after maximizing tickets for clarification.

Please send us a small sample that demonstrates how our RichEditControl is created in your real application.

Hello Yulia,
I thinking the samples does not helps… because RTF control using in many scenarios in the application, and difficult to say which one bring the freeze. Does my dump file help to understand some source of the problem? When not, maybe you can suggest the way to track OnUserPreferenceChanged event. Is it possible to log which controls from which thread subscribe it ? Then probably could be found place in the application which using Rtf or other GUI controls in separate thread.

Thanks
Denis

Hello Denis,

Our default UserLookAndFeel object subscribes to the Microsoft.Win32.SystemEvents.UserPreferenceChanged event when the first StyleChanged event handler is created. So, if the first UI control is created in a background thread, subscription to the Microsoft.Win32.SystemEvents.UserPreferenceChanged event is performed in a background thread. This may lead to the application hanging if User Preferences change when the form is alive.

C#
class UserLookAndFeelDefault : UserLookAndFeel  
      protected override void OnFirstSubscribe() {
          Microsoft.Win32.SystemEvents.UserPreferenceChanged += new Microsoft.Win32.UserPreferenceChangedEventHandler(OnUserPreferencesChanged);
      }

You may add a breakpoint into the OnFirstSubscribe method of the UserLookAndFeelDefault class and check from which thread this method is called.
See also: How can I debug DevExpress .NET source code using PDB files
Please keep us informed of your results.

I also recommend you review the Initialization of RichEdit and its Ribbons very slow ticket where the issue with the Microsoft.Win32.SystemEvents.UserPreferenceChanged event was researched.