Thunar sends thumbnail update requests to Tumbler when text is copied to the clipboard

It is easy to see this by enabling debug logging in Tumbler 4.17.0. Steps to reproduce:

• execute in a terminal

  pkill tumblerd
  G_MESSAGES_PREFIXED= G_MESSAGES_DEBUG=all /usr/lib/tumbler-1/tumblerd

• open Thunar in a directory containing files that trigger thumbnail requests;
• copy text into an application (either via keyboard shortcut or context menu), e.g. the terminal where Tumbler runs, or a text editor.

You will then see the thumbnail update requests that Tumbler receives. Close Thunar and the requests are no longer sent.