I just wanted to share an important information with you.
It is not a "fresh scoop", because it is true since -at least- v11, but after 7 years working with FileMaker (it was with v9), i just realized it this morning and it is an horrible one. So it is very possible that you missed it too :
On Windows OS only, when a dialog created by the Show Custom Dialog step is displayed, [ESC] key act as [ENTER] key. In other words, both are invoking the default button.
Suppose a such dialog :
"Are you sure to empty trash ?"
[ESC] key, as well as [Enter] key, will return 1 with Get ( LastDialogChoice ) cal function.
This morning, one of my user lost all his entries by pressing ESC two times, a bit stressed, validating two warnings without seeing them.