On a mac, when you are with the caret at the end of a line of text, how do you select the whole line of text using only the keys? On a windows PC I would use shift-home. On a mac this would be CTRL-SHIFT-A but this doesn’t work inside MonoDevelop!
MonoDevelop uses it’s own keybinding system, look it up under MonoDevelop->Preferences->Keybindings.