After some more investigation, in the non-rootless mode, Xmir sets the _MIR_WM_PERSISTENT_ID atom on the root window, and since pasted just queries the default root window, this works fine.
However, in rootless move, one of the children on the "root" window gets the _MIR_WM_PERSISTENT_ID atom, thus pasted is not able to get the persistent surface id. So, we can approach this one of two ways. 1. Xmir can set _MIR_WM_PERSISTENT_ID on the root window regardless of the mode. 2. pasted will have to get smarter and try to first query the root window and if that returns nothing, then do an XQueryTree() and iterate over child windows until the _MIR_WM_PERSISTENT_ID is found. I prefer 1 since it will offer consistency, bit I'm not sure if there are any pitfalls with that approach. Will subscribe xmir to this bug and get duflu's advice:) ** Also affects: xorg-server (Ubuntu) Importance: Undecided Status: New ** Tags added: xmir -- You received this bug notification because you are a member of Desktop Packages, which is subscribed to xorg-server in Ubuntu. https://bugs.launchpad.net/bugs/1671257 Title: Copy & paste into/from Xapps no longer works Status in Canonical System Image: New Status in Libertine: In Progress Status in Libertine devel series: In Progress Status in Libertine trunk series: Triaged Status in libertine package in Ubuntu: Triaged Status in xorg-server package in Ubuntu: New Bug description: Seems pasted is no longer working due to some change somewhere other than pasted. I suspect either Xmir -rootless mode broke this or we need the Xmir changes for supporting Mir 0.26 (or both). To manage notifications about this bug go to: https://bugs.launchpad.net/canonical-devices-system-image/+bug/1671257/+subscriptions -- Mailing list: https://launchpad.net/~desktop-packages Post to : desktop-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~desktop-packages More help : https://help.launchpad.net/ListHelp