Hi,
Your window has got the button on the top as "keyboard" , you can assign with this else
Right click a toolbar and select "Customize"
Select the "Commands" tab
Decide where you want to add this (Menu bar, Toolbar, context menu)
Click "Add Command..."
Under the "Macros" category there are:
"Macros.Samples.Utilties.TurnOffLineNumbers"
"Macros.Samples.Utilties.TurnOnLineNumbers"
Hope it helps.