Version:           4.7 (using KDE 4.7.3) 
OS:                Linux

When having a mail view (mail in separate window) opened, all source views (source of mail in separate window) will be opened in the activity of the mail view.

Reproducible: Always

Steps to Reproduce:
1. Open KMail
2. Assign the KMail window to 2 activities
3. Open a mail in a separate window
4. Switch to the other activity to which the KMail window was assigned to
5. Open the source view of a mail

Actual Results:  
The source view window of the mail is not opened in the current activity. Instead it is opened in the activity, in which the last mail view window was opened.

Expected Results:  
I'd expect the source view to be opened on the current activity.

This doesn't happen when there hasn't a mail view been opened before.
When simply opening the source view from a freshly launched KMail, the source view is also displayed on all activities on which KMail is shown (which is also wrong, as a source view as a separate window belongs only to the current activity).