Keyboard shortcuts for use in VirtualViewer are defined in config.js in the hotkeys section, as shown below:

hotkeys: {
  zoomIn: 'ctrl++,ctrl+=',
  zoomOut:'ctrl+-,ctrl+_',
  exportDocument: 'ctrl+shift+e',
  printDocument: 'ctrl+shift+p',
  lastPage: 'end',
  firstPage: 'home',
  previousPage: 'ctrl+shift+pageup',
  nextPage: 'ctrl+shift+pagedown',
  rotateCounter: 'ctrl+shift+l',
  rotateClock: 'ctrl+shift+r', s
  howKeyboardHints: 'ctrl+/',
  toggleThumbnailPanel: 'ctrl+shift+t',
  fitHeight: 'ctrl+shift+j',
  fitWidth: 'ctrl+shift+w',
  fitWindow: 'ctrl+shift+q',
  panLeft: 'left',
  panRight: 'right',
  panUp: 'up',
  panDown: 'down',
  thumbPageDown: 'ctrl+end',
  thumbPageUp: 'ctrl+shift+end',
  copyText: 'ctrl+shift+c',
  searchText: 'ctrl+shift+f',
  enterSelectTextMode: 'ctrl+shift+insert',
  toggleTextSelectionMode: 'ctrl+shift+d',
  toggleImageInfo: 'ctrl+shift+u'
},