Tested on Win10 :
If the only control on the form is the Memo then MemoExit is not called.
Yes, I said that too but, frankly, if the memo is the only control and all that is needed is to trigger its OnExit event one might as well call the handler directly from the form's OnClick one.
In fact, from the OP's description:
What I need is to store the content of controls whenever it is changed. I'm looking for the most secure way. Practically exiting control may happen in many cases .. by directly entering into another control, clicking on a form, closing the form by clickicking on the small x button, or closing form by pressing Alt-F4, etc. Just want to know any event that will be called everytime.
what I would do is to add a "SaveMemo" method to the form and call from whatever event(s) it should be called or, anyway, from the form's OnCloseQuery handler, when you
know the contents are finally fixed.
I have got a program, kind of a "notes to self/things to remember" pad, which needs to do something similar and one of the options I looked into for an "auto-save" feature was to intercept the <Enter> key (in the memo's OnKeyUp event) and save the contents then, but I finally realized it was a futile exercise and what I did was to use a TXMLPropStorage to store some session properties and to save/load the memo contents using its events. After a few false starts (first time I ever used that component) all was a piece of cake compared to, say, dealing with the shortcomings of TMemo