It’s probably more Windows than Cubase but it might be both. Whenever I change something in one of the kontakt instrument and then trying to delete it from kontakt it’s always asking if I want to save the changes. Since I installed C8 that message is always covered with kontakt it self. In order to click Ok or Cancel I have to go Alt/Tab and than just be quick enough to be able to click one of it once is automatically switching between windows.
Anybody has an idea or quick fix for it?
There’s a slight issue with the Kontakt child window asking you to confirm a yes or no to load in another instrument. But, it’s nowhere as bad a little hiccup as has been made out in some forum topics, its certainly not a “show stopper” tio stop it being used quite efficiently.
There are a number of work arounds for the time being, the tabs on the task bar is where you’ll find the child dialogue boxes, you can open and close them from there. You can also position Kontakt on you screen in a position where you will always see a fair bit of the chold dialogue box to click onto it with your mouse or, if your not going to save any changes in Kontakt, simply hit the enter key to free up the “freeze”. You can right click in the top of Kontakt and de-select “Always on top” whch will solve all, but that does not get remembered when you save a project!
It is a known issue, hss its own bug report number and will be repaired in a future update, the sooner the better, but it doesn’t stop yoy using it at all, so get on in there and post relevant things you may have found to help every one else ! 
Definitely will post any findings! Thanks.