I always felt bad adding cinemas/screens with the 'Create KDM' window, then exiting this dialog using 'Cancel', as it servers the double function of maintaining the cinema/screen database AND creating KDMs. But if I'd choose 'OK' instead, it would try to save or send KDM - possibly sending KDMs to actual cinemas, maybe unnecessary/invalid data. Therefore, also add a simple confirmation dialog before actually sending KDM email ('Are your sure you want to send KDM to xxx?').
Because cinemas could feel annoyed about 'weird' KDMs received.

While I like the idea that both - editing screen database and KDM creation is possible from the same window, I think one should change the action buttons/choices to make working with these functions more consistent GUI wise.

E.g.: Don't make 'Save KDM' and 'Email KDM' exclusive, but use checkboxes, allowing to do BOTH. And/or create individual action buttons behind every option, like 'Save KDM' and 'Send KDM' (->plus confirmation, see above).

There is no global way to escape/cancel cinema/screen changes once they are done - e.g. changing something, then leaving with 'Cancel' will leave the changes in place. Not so bad, as you can still cancel individual changes, but, as said above, it is not consistent with user expectations.

When there are individual 'Save KDM' and 'Send KDM' buttons, this window could get a single 'Close' or 'Exit' button.