Steps to reproduce:
1. Add a small button to a form.
2. On click of this button show an OpenFileDialog.
3. Add a big button to the form
4. Add some sort of notification in the big button's click event handler (RadMessageBox)
5. Run the project and open the file dialog.
6. Position the dialog so the file (inside the open file dialog) you will choose will be over the big button.
7. Select a file by double clicking on it.

You will see that the Click event for the big button will be fired.