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Asked: 2021-09-23 05:53:25 +0800 CST

Gtk clipboard owner-change event: detecting whether the changer is me

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It is easy to set the contents of the normal ctrl-C ctrl-V clipboard in Gtk 3 in a Python 3 app, with something like

clipboard = Gtk.Clipboard.get(Gdk.SELECTION_CLIPBOARD)
clipboard.set_text("It worked!, -1)

It is also easy to monitor the clipboard for changes, using the Clipboard object's owner-change signal.

However, I would like to ignore owner-change in my app if it was my app that set the contents of the clipboard, and I don't know how. The owner-change signal passes an owner parameter which points to a Gdk.Window, but I never explicitly create a window in my app; I assume that Gtk quietly creates one for me because there needs to be some X window around to own the contents of the clipboard. I can get that X window's ID when the clipboard owner changes with something like:

def clipboardChanged(clipboard, owner_change):
    print("New owner is", owner_change.owner.get_xid())

clipboard.connect('owner-change', clipboardChanged)

This new owner window obviously belongs to my app, but how do I find its xid ahead of time? That is: how can I tell from an owner-change signal that the new owner is me?

(Note: if I set the contents of the clipboard twice, I get two owner-change signals, and owner_change.reason is NEW_OWNER every time, so this is not reliable: in particular, NEW_OWNER is also sent for "the same owner set it again", and not just for "a different owner now owns the clipboard".)

python

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