Click button2up on a completion to select it.
Type M-v or prior to move to this buffer, for keyboard selection.

Possible completions are:
debug                                   debugger-jump
debug-on-entry                          debugger-list-functions
debugger-continue                       debugger-make-xrefs
debugger-eval-expression                debugger-record-expression
debugger-frame                          debugger-return-value
debugger-frame-clear                    debugger-step-throug