Press
Ctrl+`
to show information about the operator in the current form, in a displayer window on top of the Editor. The displayer shows the operator and its arguments, and tries to highlight the argument at the cursor position using the style Arglist Highlight.
While the displayer is visible:
Ctrl+/
controls whether the documentation string of the operator is also shown
Ctrl++
moves the displayer up
Ctrl+-
moves the displayer down