When logout from your KDE desktop, leaving running applications on different activieties, and log on again, session management restores all active windows to that activity which finally had focus. This causes quite a lot of unnecessary work:




Reproducible: Always

Steps to Reproduce:
To move n windows do different actitiy/activities, today you need 6n user actions

For w in windows:
    Right click title bar
    select activities submenu
    select desired target activity.
    Right click title bar
    select activities submenu
    select current activity


Actual Results:  
To move n windows do different actitiy/activities, today you need 6n user actions

Expected Results:  
It should be as straightforward as moving files to trashcan or different folders, 
hence you just need to perform 1/3 (2n instead of 6n) handling actions:

a) a drag&drop approach:
For w in windows:
    1) select Window anywhere by alt-clicking (as if to move it)
    2) drag and drop it to a small activity drop-zone on a (small) plasmoid on the task bar
    
- OR -
b) a shortcut based approach
For w in windows:
    1) focus a window (by any of the common methods: click, alt-tab, ...)
    2) press a shortcut defined to send it onto the desired activity

Also see https://bugs.kde.org/show_bug.cgi?id=308475, where this suggestion originates from.