In the old versions of .NET, we needed to override the default context menu and override the
ProcessCmdKeyfunction to return True to disable Copy-Paste of content into textboxes through keys such as Ctrl+C, Ctrl+V, Shift+Insert, etc.
In the newer versions of .NET, we can just disable the “ShortcutsEnabled” property to False. This will do the trick. You can no longer copy/paste or perform any other actions through shortcuts on the textbox.