Sometimes when kwin crashes,, when it starts up again ALL windows from ALL activities get dumped into All Activities. This is despite this info having persisted across over many days and across several system restarts, it just loses all activity session data. 

Reproducible: Sometimes

Actual Results:  
On restart of kwin all windows are in Al Activities

Expected Results:  
On restart of kwin each window should be assigned to the same activity or activities to which is was assigned before the crash.

This is extremely discouraging to someone trying to use activities to their fullest potential with many windows carefully sorted amongst different activitis. Kwin should guard against this happening. I assume it occurs if the crash occurs at a moment when it is saving this information to disk, perhaps corrupting it. This could be protectd against by always backin up and maintaining the last copy before rewriting it, ideally the last several copies.