<function name="OnUndo" parent="GM" type="hook"> <description>Called when the player undoes something.</description> <file line="46-L74">gamemodes/sandbox/gamemode/cl_init.lua</file>⤶ <realm>Client</realm> <args> <arg name="name" type="string">The name of the undo action</arg> <arg name="customText" type="string">The custom text for the undo, set by <page>undo.SetCustomUndoText</page></arg> </args> <rets> <ret name="suppress" type="boolean">Return false to suppress the undo notification. </ret> </rets> </function> <example> <description>Print a message when the player undoes something.</description> <code> hook.Add( "OnUndo", "CustomUndoText", function( name, customText ) if customText ~= nil then MsgN( "Undone " .. customText ) else MsgN( "Undone " .. name ) end end ) </code> <output>Undone &lt;action&gt;</output> </example>