This extension coaches you and teaches you all the Visual Studio hotkeys slowly, by showing you the hotkey of any action you invoke.
It could be that you wanted to click the "comment line" button. In that case, this plugin will briefly (in a non-disturbing semi-transparent manner) show "CTRL + K, C" in a dialog for 5 seconds, allowing you to memorize the hotkey for the action.
https://marketplace.visualstudio.com/items?itemName=MathiasLykkegaardLorenzen.ShortcutCommanderVSIX