The main purpose of a button is being clicked.
That may occurs by using a mouse, via a touch device or by hitting the spacebar or the enter key on a keyboard.
The usual appearence for a <pacem-button> is obtained by adding the button class.
The content of a button can be preceded by a material icon glyph (iconGlyph property).
Here are other common button-relevant looks:
Buttons can be lined-up in a button-set.
A PacemButtonElement can be bound to a dialog, in order to request confirmation before the very execution and discard it, eventually.
PacemButtonElement implements the command pattern; just manage the relevant observable properties (commandName, commandArgument)
and event (command).