Issue with Qtractor (PPA) and Debian GNOME.

Forums

Hi,
I followed the PPA recommendation from this forum (https://www.rncbc.org/drupal/index.php/node/2891), and so far, I haven't had any issues with Qtractor on Debian or MX Linux. However, I had always used KDE previously—whether with the standard Debian kernel or one of the Liquorix variants. As the title suggests, a problem arises on Debian and MX when installing GNOME from the Debian or MX repositories. I initially tried only MX and thought the issue might be related to installing GNOME on top of XFCE. Afterward, I tried a Debian netinstall with the standard kernel, GNOME, and Qtractor (via PPAs), but Qtractor won't launch—regardless of whether I'm using Wayland or X11. There are no issues with Arch + GNOME, even though it runs exclusively on Wayland. KDE remains trouble-free as well, whether on Arch or Debian, and regardless of whether X11 or Wayland is used. The other problematic combination is Arch+LXQt + Labwc + Qtractor (crashes, freezes), but that isn't the issue I'm dealing with right now. When I start Qtractor in the terminal I get the following messages:
"qtractor
Gtk message: 14:34:54.491: Failed to load module "canberra-gtk-module"

(qtractor:5150): GLib-GObject-CRITICAL **: 14:34:54.527: cannot register existing type 'GtkWidget'

(qtractor:5150): GLib-GObject-CRITICAL **: 14:34:54.527: cannot add class private field to invalid type ''

(qtractor:5150): GLib-GObject-CRITICAL **: 14:34:54.529: cannot add private field to invalid (non-instantiatable) type ''

(qtractor:5150): GLib-GObject-CRITICAL **: 14:34:54.529: g_type_add_interface_static: assertion 'G_TYPE_IS_INSTANTIATABLE (instance_type)' failed

(qtractor:5150): GLib-GObject-CRITICAL **: 14:34:54.529: cannot register existing type 'GtkBuildable'

(qtractor:5150): GLib-GObject-CRITICAL **: 14:34:54.529: g_type_interface_add_prerequisite: assertion 'G_TYPE_IS_INTERFACE (interface_type)' failed

(qtractor:5150): GLib-CRITICAL **: 14:34:54.529: g_once_init_leave: assertion 'result != 0' failed

(qtractor:5150): GLib-GObject-CRITICAL **: 14:34:54.529: g_type_add_interface_static: assertion 'G_TYPE_IS_INSTANTIATABLE (instance_type)' failed

(qtractor:5150): Gtk-CRITICAL **: 14:34:54.529: gtk_widget_get_style_context: assertion 'GTK_IS_WIDGET (widget)' failed

(qtractor:5150): Gtk-CRITICAL **: 14:34:54.529: gtk_style_context_lookup_color: assertion 'GTK_IS_STYLE_CONTEXT (context)' failed

(qtractor:5150): Gtk-CRITICAL **: 14:34:54.529: gtk_style_context_get_background_color: assertion 'GTK_IS_STYLE_CONTEXT (context)' failed

(qtractor:5150): GLib-GObject-CRITICAL **: 14:34:54.529: cannot register existing type 'GtkWidget'

(qtractor:5150): GLib-GObject-CRITICAL **: 14:34:54.529: cannot add class private field to invalid type ''

(qtractor:5150): GLib-GObject-CRITICAL **: 14:34:54.529: cannot add private field to invalid (non-instantiatable) type ''

(qtractor:5150): GLib-GObject-CRITICAL **: 14:34:54.529: g_type_add_interface_static: assertion 'G_TYPE_IS_INSTANTIATABLE (instance_type)' failed"

I hope this is easy to fix?
I also had an error message with canberra-gtk3-module and reinstalled it. Unfortunately, that didn't help.

Many thanks in advance!

re. Issue with Qtractor

Try with:

https://sourceforge.net/p/qtractor/wiki/How%20To%20-%2011%20Prevent%20Color%20Picker%20Freezing%20Qtractor/

PS:
I prefer XFCE because it allows you to send windows to the background (and generally I prefer the classic approach, though that is a matter of taste). In Qtractor, this is useful for ensuring that the sequencer always stays behind other windows.

PS 2:
Theoretically, just running
export QT_QPA_PLATFORMTHEME=qt6ct

shouldn't work reliably—it would only be temporary. You would normally need to add it to a configuration file (I don't recall which one right now). But apparently—or at least in my case—it works. It must be something qt6ct handles automatically.

re1. Issue with Qtractor

To summarize:

Install qt6ct (I believe it is compiled for Qt6 on Noble).
Reboot.

The problem should be resolved.

If not, get a qtractor desktop file:
https://github.com/rncbc/qtractor/blob/main/src/appdata/org.rncbc.qtractor.desktop

Edit the Exec line like this:
Exec=env QT_QPA_PLATFORMTHEME=qt6ct qtractor -platform xcb %f

And save it to:
~/.local/share/applications/

That will launch qtractor correctly.

Note:
If you created shortcuts elsewhere—such as on desktop panels or the desktop itself—you will need to delete them and replace them with the new one; at least in XFCE—I’m not sure if GNOME automates that.

re2. Issue with Qtractor...

Edit the Exec line like this:
Exec=env QT_QPA_PLATFORMTHEME=qt6ct qtractor -platform xcb %f

mind you, the particle -platform xcb is not really necessary: qtractor always runs on xcb adapter anyway

otherwise no plugin GUI would show up as it should, no matter it runs under a X11 or wayland session ;)

br.

Add new comment

Your name

The content of this field is kept private and will not be shown publicly.

Homepage

Comment

Text format

Markdown

Parses markdown and converts it to HTML.
Allowed HTML tags: <a href hreflang> <em> <strong> <cite> <blockquote cite> <code> <ul type> <ol start type='1 A I'> <li> <dl> <dt> <dd> <h2 id='jump-*'> <h3 id> <h4 id> <h5 id> <h6 id> <img src alt height width> <strike> <pre> <p> <br>
Lines and paragraphs break automatically.

Filtered HTML

Allowed HTML tags: <a href hreflang> <em> <strong> <cite> <code> <ul type> <ol start type> <li> <dl> <dt> <dd> <b> <i> <pre> <img src alt height width> <strike>
Lines and paragraphs break automatically.
Web page addresses and email addresses turn into links automatically.

Plain text

No HTML tags allowed.
Lines and paragraphs break automatically.
Web page addresses and email addresses turn into links automatically.

Add new comment