Once turned on and turned off the desktop effects was a change in the settings windows, always open windows in the maximum amount for all programs. How to Recover the initial setting?
I’ve not tried that but I’ve always found that, if I change the size of a window, most applications remember that size and re-open in that size when I next log in. If turning off all desktop effects has the effect you describe, why not reinstate one that doesn’t trouble you as a workaround and put in a bug report?
Try if you find something in:
‘Personal Setting’ > ‘Window Behaviour’ > ‘Window Behaviour’
Espcially the settings for ‘Placement’ (Tab: ‘Advanced’) look like a likely culprit.
I tried probably everything from System settings> Windows but failed.
Obviously I did not hit 
Maybe you have Tiling enabled?
If all else fails you can always delete/remove preferences. The directory ‘~/.kde4’ (in your user’s home) contains all KDE related preferences. But you don’t necessarily have to remove the whole thing. You could first comb through ‘~/.kde4/share/config’ and ‘~/.kde4/share/apps’ and look for likely culprits.
Kde: unvoluntarily set kwin layout to spiral
this is a decision
ALT+SHIFT+F11 is a toggle (just like ALT+SHIFT+F12), press it again and the window positioning will go back to normal
or
System settings> Windows>Window>Advanced>Tiling disable
Thanks Lord_Emsworth!