FNC Edit - SelectAll not working

TTMSFNCEdit function is not working.
only place a control and run the .SelectAll;
it should have had selected all text;

for SelectAll to be working, the edit needs to be focused. SelectAll does not automatically focus the edit.

TMSFNCEdit1.SetFocus;
TMSFNCEdit1.SelectAll;

This is the same behavior as TEdit

But if I use this code inside OnChange. There is no effect. I need to select all text after it being changed.

I don't see how this can be done. In TEdit, this is also not working. You might want to change your code to the OnExit event, because while editing, I don't think this is supposed to work.