Multi-window GTK apps in Mir are randomly unresponsive, seem to freeze

[Daniel van Vugt]

GTK apps on Mir: Input focus is unreliable and sporadic. Background windows ignore input and/or focus switches apparently randomly.

Example:

$ GDK_BACKEND=mir mir_demo_server --launch gnome-mahjongg

Show the "Scores" - you can switch focus between this and the main window with Alt+` but doesn't respond to input.

Other dialogs (e.g. "About") work fine. From the Mir side there's no obvious difference between these windows.

In this example, MIR_CLIENT_INPUT_RECEIVER_REPORT=log shows the input events being correctly received on the client side. That shows most of the Mir stack is working correctly.

[Daniel van Vugt (vanvugt)]

It's possible this is not an input or focus issue at all. It's possible GTK is failing to notify Mir of some window redraws in multi-window apps so some windows (sometimes) appear to freeze.

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Emanuele Antonio Faraone (emanueleant03)]

+1

[Will Cooke (willcooke)]

Added to Trello: https://trello.com/c/a8vjKoJX/12-bug-1445543-multi-window-gtk-apps-in-mir-are-randomly-unresponsive-seem-to-freeze

[Alan Griffiths (alan-griffiths)]

Seems to be working with gtk 3 on zesty - so not Mir.

[Daniel van Vugt (vanvugt)]

Incomplete. I can still reproduce a freeze using the instructions in the description but it also looks like those instructions are wrong. Because if you do the same in X you will fine the Scores dialog is modal and is meant to make the main window unresponsive to input.

That said, I also remember anpok saying he found and fixed a reason for bugs like this in GTK.

[Daniel van Vugt (vanvugt)]

*you will find*

[Andreas Pokorny (andreas-pokorny)]

GdkMir needs fixing here:

https://github.com/GNOME/gtk/blob/master/gdk/mir/gdkmirwindowimpl.c#L1066

and maybe this:
https://github.com/GNOME/gtk/blob/master/gdk/mir/gdkmirwindowimpl.c#L882

[Andreas Pokorny (andreas-pokorny)]

Ok this needs clarification - the dialogs we are talking about are not frozen in the current state of gdkmir, but not behaving correctly - they should be modal but are not.

[Daniel van Vugt (vanvugt)]

Does Mir have the required client API functions for those yet?