dialog boxes don't always have the horizontal rule above the command buttons

[Jeff Almasol]

some dialogs have a horizontal rule to separate the body of the dialog from the command buttons at the bottom, but some don't (e.g., Icon, Delete confirmation dialogs). unsure what's intended.

[Rafi Khan]

Dialogs with fixed height(s) don't have the HR. Variable height dialogs that can grow dynamically (like expressions/scriptlets) have them.

[Rafi Khan]

Nothing to do here.